A method and apparatus for treating ammonia-containing tail gas using CO2

Abstract

The application provides a method and device for treating ammonia-containing tail gas by using CO2. The method comprises the following steps: dissolving CO2 in water to obtain a carbonic acid solution; performing first reverse contact between the carbonic acid solution and ammonia-containing tail gas to be treated to obtain first absorption liquid and absorbed tail gas, and performing discharge treatment on the absorbed tail gas; circulating at least part of the first absorption liquid to participate in the first reverse contact; the ratio of the NH3 content in the ammonia-containing tail gas, the mass of CO2 dissolved in water per unit time, the mass of water per unit time and the mass of the first absorption liquid circulating to participate in the first reverse contact per unit time is (500-1800):(15-750):(5600-15500):(140000-1200000). The method uses surplus CO2 to absorb NH3 in the ammonia-containing tail gas, and the NH3 content in the treated ammonia-containing tail gas is not higher than 50 mg / Nm 3 , which can be directly discharged at a high point to reduce carbon emission, and can also be used to prepare ammonium bicarbonate and / or ammonium carbonate products, and has good green environmental protection value and application prospect.

Description

Technical Field

[0001] This invention belongs to the field of ammonia-containing tail gas treatment technology, specifically relating to a method and apparatus for treating ammonia-containing tail gas using CO2. Background Technology

[0002] NH3 is a typical organic waste gas, with a wide range of sources including coke oven gas, ammonia refrigeration tank exhaust, nitric acid plant tail gas, and other industrial production. However, the main source of ammonia-containing tail gas is the soda ash production plant. The soda ash process was developed based on the ammonia-soda process, and its initial purpose was to solve the problem of large amounts of waste liquid and residue discharged from the ammonia-soda process. Therefore, compared with the ammonia-soda process, the soda ash process has the advantages of higher sodium chloride utilization, lower waste liquid and residue discharge, and lower energy consumption.

[0003] However, in actual production, due to relatively outdated technology and equipment, and weak production operation and supervision, most soda ash production enterprises experience large amounts of ammonia-containing tail gas being released into the atmosphere. This includes ammonia tail gas from heavy soda ash, soda ash, calcination, and ammonium chloride production. The direct release of large amounts of ammonia-containing tail gas into the atmosphere not only results in the loss of ammonia products but also pollutes the environment and harms human health. Eliminating ammonia pollution has become a focus of attention in the domestic and international environmental protection field, and countries around the world have successively promulgated laws to regulate its emissions. Currently, the emission standard for ammonia-containing tail gas is the "GB 14554-93 Odor Pollutant Emission Standard," which clearly stipulates the emission limits for ammonia-containing tail gas at different emission heights.

[0004] However, the industry mainly uses soft water to purify and remove NH3 from ammonia-containing exhaust gases. This method not only consumes a huge amount of water, but also still results in ammonia emissions exceeding national standards, which has a serious impact on the environment and the health of factory workers.

[0005] Therefore, there is an urgent need to develop a highly efficient method for treating ammonia-containing exhaust gas that is widely applicable, uses less water, and reduces costs and increases efficiency, so as to meet emission standards. Summary of the Invention

[0006] This invention provides a method for treating ammonia-containing exhaust gas using CO2, in order to solve the problem that removing NH3 through soft water purification requires a huge amount of water and that NH3 emissions still exceed national standards.

[0007] This invention provides an apparatus for treating ammonia-containing exhaust gas using CO2, which is used to perform a method for treating ammonia-containing exhaust gas using CO2, solving the problems of water wastage and low treatment efficiency in soft water purification and NH3 removal.

[0008] The present invention also provides a production system including the above-mentioned device for treating ammonia-containing tail gas using CO2. This production system can achieve efficient absorption of ammonia tail gas at a lower cost, with significant cost reduction and efficiency improvement effects.

[0009] On one hand, the present invention provides a method for treating ammonia-containing tail gas using CO2, comprising the following steps:

[0010] CO2 is dissolved in water to obtain a carbonic acid solution;

[0011] The carbonated solution is brought into a first counter-current contact with the ammonia-containing tail gas to be treated to obtain a first absorbent liquid and the absorbed tail gas, and the absorbed tail gas is then discharged.

[0012] At least a portion of the first absorbent liquid is circulated to participate in the first reverse contact;

[0013] The ratio of the NH3 content in the ammonia-containing tail gas, the mass of CO2 dissolved in water per unit time, the mass of water per unit time, and the mass of the first absorbent circulating in the first reverse contact per unit time is (500-1800):(15-750):(5600-15500):(140000-1200000).

[0014] Furthermore, the first absorbent liquid includes a circulation section and an absorption section, wherein the circulation section cyclically participates in the first reverse contact;

[0015] The absorption portion undergoes a second reverse contact with the undissolved CO2 in the dissolution process to obtain a second absorption liquid;

[0016] The second absorbent liquid circulates and participates in the first reverse contact.

[0017] Furthermore, the flow rate ratio of the circulation section to the absorption section is (0.17~0.24):1.

[0018] Furthermore, the first absorbent liquid also includes a product portion; the flow rate ratio of the circulation portion, the absorption portion, and the product portion is (12-27):(58-114):(1-3).

[0019] Furthermore, the product is partially concentrated, crystallized and dried to obtain ammonium bicarbonate and / or ammonium carbonate products.

[0020] Further, the CO2 is pressurized to 1236-1366 kPa and then dissolved in water; wherein the dissolution treatment is performed at a pressure of 95-105 kPa and a temperature of 35-45°C; and / or,

[0021] The ammonia-containing tail gas is pressurized to 95-105 kPa and then subjected to the first reverse contact with the carbonic acid solution. The pressure of the first reverse contact is 95-105 kPa, and the temperature is 35-45°C; and / or,

[0022] The pressure of the second reverse contact is 95-105 kPa, and the temperature is 35-45℃.

[0023] On the other hand, the present invention provides an apparatus for treating ammonia-containing tail gas using CO2, for performing the above-described method for treating ammonia-containing tail gas using CO2; the apparatus includes a dissolution unit and an absorption unit, the dissolution unit includes a CO2 inlet, a water inlet and a carbonic acid solution outlet; the absorption unit includes a carbonic acid solution inlet, an ammonia-containing tail gas inlet, an outlet for the absorbed tail gas, a first absorbent liquid outlet and a circulating liquid inlet, and the carbonic acid solution inlet and the ammonia-containing tail gas inlet are arranged in opposite directions;

[0024] The carbonate solution outlet is connected to the carbonate solution inlet, and the first absorbent outlet is connected to the circulating liquid inlet.

[0025] Furthermore, it also includes a second dissolving unit, which includes an undissolved CO2 inlet, a low-concentration CO2 outlet, an absorption portion inlet, and a second absorbent outlet; and the absorption portion inlet and the undissolved CO2 inlet are not arranged in the same direction; the dissolving unit also includes a CO2 outlet;

[0026] The CO2 outlet is connected to the undissolved CO2 inlet, the first absorbent outlet is connected to the absorbent portion inlet, and the second absorbent outlet is connected to the circulating liquid inlet.

[0027] Furthermore, the dissolving unit includes a washing tower; the absorption unit includes an ammonia absorption tower; and the second dissolving unit includes a washing tower.

[0028] In another aspect, the present invention also provides a production system including the above-mentioned apparatus for treating ammonia-containing tail gas using CO2.

[0029] This invention provides a method for treating ammonia-containing exhaust gas using CO2. Excess CO2 is used to absorb NH3 from the ammonia-containing exhaust gas, and the NH3 content in the treated exhaust gas is no higher than 50 mg / Nm³. 3 It can be directly discharged into the air at high points, saving a lot of water and reducing carbon emissions, which helps to achieve the "dual carbon" goal. It can also be used to produce ammonium bicarbonate and / or ammonium carbonate products, achieving the effect of cost reduction and efficiency improvement, and has good green environmental protection value and application prospects.

[0030] The present invention also provides an apparatus for treating ammonia-containing tail gas using CO2, which assists in realizing the above-mentioned method of treating ammonia-containing tail gas using CO2, and effectively reduces the NH3 content in the ammonia-containing tail gas.

[0031] This invention also provides a production system including the aforementioned device for treating ammonia-containing tail gas using CO2, which achieves the requirements for tail gas treatment and carbon emission reduction, helps to achieve the "dual carbon" goal, and also achieves the effect of cost reduction and efficiency improvement, with good green environmental protection value and application prospects. Attached Figure Description

[0032] Figure 1 A schematic diagram of an apparatus for treating ammonia-containing tail gas using CO2, provided by the present invention;

[0033] Figure 2 This is a schematic diagram of a device for treating ammonia-containing tail gas using CO2 in a specific embodiment of the present invention.

[0034] Figure 3 This is a schematic diagram of another device for treating ammonia-containing tail gas using CO2, provided by the present invention.

[0035] Figure 4 This is a schematic diagram of an apparatus for treating ammonia-containing tail gas using CO2 in another specific embodiment of the present invention.

[0036] Figure 5 This is a schematic diagram of the apparatus for treating ammonia-containing tail gas in Comparative Example 1 of the present invention.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1: Absorption unit; 2: Second dissolution unit; 3: Dissolution unit; 01: Ammonia absorption tower;

[0039] 02: Secondary scrubbing tower; 03: Primary scrubbing tower; 11: Ammonia induced draft fan; 12: Absorber product pump; 13: Booster pump; 14: Circulating preheater; 15: CO2 induced draft fan; 16: Primary discharge pump; 17: Secondary discharge pump; 18: Feed preheater. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0041] On one hand, the present invention provides a method for treating ammonia-containing tail gas using CO2, comprising the following steps:

[0042] CO2 is dissolved in water to obtain a carbonic acid solution;

[0043] The carbonic acid solution is brought into a first counter-current contact with the ammonia-containing tail gas to be treated to obtain a first absorbent liquid and the absorbed tail gas. The absorbed tail gas is then treated for emission.

[0044] At least a portion of the first absorbent liquid is circulated to participate in the first reverse contact;

[0045] The ratio of the NH3 content in the ammonia-containing tail gas, the mass of CO2 dissolved in water per unit time, the mass of water per unit time, and the mass of the first absorbent circulating in the first reverse contact per unit time is (500-1800):(15-750):(5600-15500):(140000-1200000). In this invention, the CO2 comes from surplus CO2 within the production plant area, and the water used is production water. The CO2 is dissolved by contacting the production water to obtain a carbonic acid solution. Using this carbonic acid solution as a raw material for NH3 absorption rationally utilizes the surplus CO2 within the plant area, contributing to the achievement of the "dual carbon" target. During the dissolution process, a reverse contact method between CO2 and production water can be used to further enhance solubility, thereby facilitating the efficient absorption of ammonia.

[0046] The ammonia-containing tail gas to be treated in this invention mainly comes from at least one of the following: heavy alkali ammonia tail gas, soda ash ammonia tail gas, calcined ammonia tail gas, and ammonium chloride ammonia tail gas. However, this invention does not limit the type of ammonia-containing tail gas and is applicable to the treatment of all ammonia-containing waste gas.

[0047] A carbonic acid solution is brought into a first counter-current contact with the ammonia-containing tail gas to be treated, resulting in a first absorbent liquid and the absorbed tail gas. The absorbed tail gas is then treated for emission. This invention utilizes the carbonic acid solution to absorb NH3 from the ammonia-containing tail gas, ensuring that the absorbed tail gas meets emission standards and can be directly discharged at a high point. The ammonia dissolves in the carbonic acid solution to obtain a first absorbent liquid whose main components are ammonium bicarbonate and / or ammonium carbonate. At least a portion of the first absorbent liquid serves as an auxiliary agent to the carbonic acid solution, circulating and participating in the first counter-current contact to further remove NH3 from the ammonia-containing tail gas.

[0048] It should be noted that the above method is a continuous absorption method. That is, by continuously introducing carbon dioxide and water to ensure the uninterrupted operation of dissolution treatment, the first reverse contact, and at least part of the first absorbent circulation, the continuously emitted ammonia-containing tail gas can be absorbed and treated.

[0049] In the above treatment method, the ratio of the NH3 content in the ammonia-containing tail gas, the mass of CO2 dissolved in water per unit time, the mass of water per unit time, and the mass of the first absorbent circulating in the first reverse contact per unit time is (500-1800):(15-750):(5600-15500):(140000-1200000). It is understandable that, due to the complex composition of ammonia-containing tail gas and the non-constant nature of tail gas generated in factory production, in order to achieve lower-cost treatment of ammonia-containing tail gas, the inventors used the NH3 content in the ammonia-containing tail gas as a starting point. By limiting the mass ratio of the NH3 content in the ammonia-containing tail gas, the mass of CO2 dissolved in water per unit time, the mass of water per unit time, and the mass of the first absorbent circulating in the first reverse contact per unit time, they achieved efficient absorption of ammonia in the ammonia-containing tail gas. Specifically, the NH3 content in the tail gas after absorption is only 2.8%-10% of the ammonia content in the ammonia-containing tail gas to be treated. In practical applications, the mass of CO2 dissolved in water per unit time can be adjusted by controlling the pressure and temperature of the dissolution process.

[0050] This invention provides a method for treating ammonia-containing tail gas using CO2. The method utilizes CO2 and water to create a carbonated solution that absorbs NH3 from the ammonia-containing tail gas, generating ammonium bicarbonate and / or ammonium carbonate solutions. A portion of the ammonium bicarbonate and / or ammonium carbonate solutions is recycled to participate in the treatment of the ammonia-containing tail gas. This method not only achieves efficient absorption of NH3 from the ammonia-containing tail gas with lower water consumption but also produces ammonium carbonate / ammonium bicarbonate products. It also fully utilizes surplus CO2 within the plant area, reducing carbon emissions and contributing to the achievement of "dual carbon" goals, while simultaneously achieving cost reduction and efficiency improvement.

[0051] Furthermore, the treatment method of the present invention does not limit the NH3 content in the ammonia-containing tail gas to be treated, and it can be up to a maximum of 1800 mg / Nm³. 3 .

[0052] In one specific embodiment, the first absorbent includes a circulation section and an absorption section, wherein the circulation section cyclically participates in the first reverse contact; the absorption section undergoes a second reverse contact with undissolved CO2 in the dissolution treatment to obtain a second absorbent; the second absorbent cyclically participates in the first reverse contact.

[0053] It is understandable that during the dissolution process, some of the introduced CO2 will not dissolve in the water. Therefore, in order to further utilize this undissolved CO2, it can be absorbed again to form a carbonic acid solution.

[0054] Specifically, the first absorbent can be divided into two parts: a circulation part and an absorption part. The circulation part participates in the first reverse contact to further remove NH3 from the ammonia-containing tail gas and further generate ammonium bicarbonate and / or ammonium carbonate. The absorption part is used to absorb and dissolve undissolved CO2 during the dissolution treatment, so that CO2 is further dissolved in the first absorbent and further generates a carbonic acid solution to obtain the second absorbent. The second absorbent is then circulated to participate in the first reverse contact again, making full use of CO2 to absorb and remove the NH3 content from the ammonia-containing tail gas.

[0055] It is understandable that the undissolved CO2 and the absorption portion together form a second reverse contact. At this point, most of the undissolved CO2 is dissolved in the absorption portion, and the remaining small amount of low-concentration CO2 can be directly released into the air at a high point, effectively reducing carbon emissions.

[0056] Furthermore, the flow rate ratio of the recirculation section to the absorption section is (0.17–0.24):1. It is understandable that when an increase in the NH3 content in the exhaust gas after absorption is detected, the proportion of the absorption section can be increased to further absorb CO2 and generate a carbonic acid solution, which can then participate in the first reverse contact for further treatment of ammonia-containing exhaust gas. Therefore, by appropriately distributing the first absorbent liquid, water conservation can be further achieved, resulting in efficient treatment of ammonia-containing exhaust gas.

[0057] In one specific embodiment, besides dividing the first absorbent into a circulation section and an absorption section, the first absorbent can also be used as a product of ammonium bicarbonate and / or ammonium carbonate; that is, a portion of the first absorbent can also be used as a product. During the specific treatment of ammonia-containing tail gas, the application of the first absorbent can be adjusted at any time according to the NH3 content in the ammonia-containing tail gas and the target NH3 content in the tail gas after absorption. When the NH3 content in the ammonia-containing tail gas decreases, or when the target NH3 content in the tail gas after absorption is not high, the first absorbent can be divided into three parts: a circulation section, an absorption section, and a product section. The product section is used to obtain ammonium bicarbonate and / or ammonium carbonate byproducts, effectively utilizing the NH3 in the ammonia-containing waste gas and converting it into a resource product, thereby further achieving the goal of cost reduction and efficiency improvement.

[0058] In this process, the inventors adjusted the flow rates of the three parts. When the flow rate ratio of the circulation section, the absorption section, and the product section is (12-27):(58-114):(1-3), the treatment effect of ammonia-containing waste gas and the resource output of by-products can be balanced to the greatest extent.

[0059] This invention does not limit the post-processing method of the product, as long as it can be converted into ammonium bicarbonate and / or ammonium carbonate products with a purity of not less than 99%.

[0060] In one specific embodiment, the product portion may be subjected to operations such as concentration, crystallization, and drying to ultimately obtain ammonium bicarbonate and / or ammonium carbonate products.

[0061] Furthermore, by further limiting the execution parameters of the dissolution treatment, the first reverse contact, and the second reverse contact, the concentration of reactants can be increased by pressurization, thereby increasing the absorption efficiency and also having a certain positive promoting effect on the treatment of NH3 in ammonia-containing tail gas.

[0062] In one specific embodiment, CO2 is pressurized to 1236-1366 kPa and then dissolved in water; wherein the dissolution treatment pressure is 95-105 kPa and the temperature is 35-45℃.

[0063] In another specific embodiment, the ammonia-containing tail gas is pressurized to 90-105 kPa and then subjected to a first reverse contact with a carbonic acid solution. The pressure of the first reverse contact is 95-105 kPa and the temperature is 35-45°C.

[0064] In another specific embodiment, the pressure of the second reverse contact is 95-105 kPa and the temperature is 35-45°C.

[0065] On the other hand, the present invention provides an apparatus for treating ammonia-containing tail gas using CO2, for performing the above-described method for treating ammonia-containing tail gas using CO2; Figure 1 This is a schematic diagram of an apparatus for treating ammonia-containing tail gas using CO2, provided by the present invention. Figure 1 As shown, the device includes a dissolution unit 3 and an absorption unit 1. The dissolution unit 3 includes a CO2 inlet, a water inlet, and a carbonic acid solution outlet. The absorption unit 1 includes a carbonic acid solution inlet, an ammonia-containing tail gas inlet, an absorption tail gas outlet, a first absorbent liquid outlet, and a circulating liquid inlet. The carbonic acid solution inlet and the ammonia-containing tail gas inlet are not arranged in the same direction. The carbonic acid solution outlet is connected to the carbonic acid solution inlet, and the first absorbent liquid outlet is connected to the circulating liquid inlet.

[0066] It is understood that the present invention does not limit the connection method between the various units, as long as it allows for the smooth flow of materials. In one specific embodiment, the various units are connected by pipes.

[0067] The present invention does not limit the form of each unit. The dissolving unit 3 can provide the function of dissolving CO2 in water to generate a carbonic acid solution; the absorption unit 1 can provide the function of contacting the carbonic acid solution with the ammonia-containing tail gas.

[0068] It is understood that the dissolving unit 3 includes at least a CO2 inlet, a water inlet, and a carbonic acid solution outlet. CO2 enters the dissolving unit 3 through the CO2 inlet, water enters the dissolving unit 3 through the water inlet, and the carbonic acid solution generated in the dissolving unit 3 leaves the dissolving unit 3 through the carbonic acid solution outlet. Preferably, in order to ensure sufficient contact between CO2 and water, the CO2 inlet can be located at the bottom of the dissolving unit, and the water inlet can be located at the top of the dissolving unit, so that gravity allows the two to flow in opposite directions and achieve sufficient contact.

[0069] The absorption unit 1 includes at least a carbonate solution inlet, an ammonia-containing tail gas inlet, a post-absorption tail gas outlet, a first absorbent liquid outlet, and a circulating liquid inlet. It is understood that the carbonate solution enters the absorption unit 1 through the carbonate solution inlet, and the ammonia-containing tail gas enters the absorption unit 1 through the ammonia-containing tail gas inlet. Similarly, to ensure sufficient material contact and absorption, the carbonate solution inlet and the ammonia-containing tail gas inlet are not arranged in the same direction. This invention does not specifically limit the method of non-co-directional arrangement; any method that enables the two to achieve a flow effect in opposite directions is acceptable. For example, the ammonia-containing tail gas inlet can be located at the bottom of the absorption unit 1, and the carbonate solution inlet can be located at the top of the absorption unit 1, allowing them to flow in opposite directions and make sufficient contact. Furthermore, the first absorbent liquid flowing out of the absorption unit 1 is discharged through the first absorbent liquid outlet, and the treated tail gas is discharged through the post-absorption tail gas outlet. To allow some of the first absorbent liquid to return to the absorption unit 1, a circulating liquid inlet is also provided, ensuring sufficient ammonia removal treatment of the ammonia-containing tail gas and saving water resources through water recycling.

[0070] Furthermore, the carbonated solution flows out of the dissolving unit 3 via the carbonated solution outlet and then enters the absorption unit via the carbonated solution inlet. The first absorbent flows out of the absorption unit 1 via the first absorbent outlet and then re-enters the absorption unit 1 via the circulating liquid inlet.

[0071] It is understood that the first absorbent liquid can also be directly used to produce by-products; therefore, the pipeline connected to the outlet of the first absorbent liquid is also provided with an outlet connecting to the outside. In one specific embodiment, such as... Figure 2 As shown, the dissolution unit includes a primary washing tower 03, a CO2 induced draft fan 15, and a primary discharge pump 16; wherein, the primary washing tower 03 has a CO2 inlet at the bottom, a water inlet at the top, and a carbonate solution outlet at the bottom, and the primary washing tower 03 is a packed tower; the absorption unit includes an ammonia absorption tower 01, an ammonia induced draft fan 11, an absorption tower product pump 12, and a circulating preheater 14; wherein, the ammonia absorption tower 01 has a carbonate solution inlet at the top, an ammonia-containing tail gas inlet at the bottom, a tail gas outlet after absorption at the top, a first absorbent liquid outlet at the bottom, and circulating liquid inlets at the middle and lower sections, and the ammonia absorption tower 01 has a plate tower at the top, and a packed tower at the middle and lower sections;

[0072] Furthermore, such as Figure 2As shown, the carbonic acid solution outlet is connected to the carbonic acid solution inlet, and the first absorbent liquid outlet is connected to the circulating liquid inlet; the CO2 induced draft fan 15 is installed on the pipeline connected to the CO2 inlet, the primary discharge pump 16 is installed on the pipeline connected to the carbonic acid solution outlet and the carbonic acid solution inlet, the ammonia induced draft fan 11 is installed on the pipeline connected to the ammonia-containing tail gas inlet, the absorber product pump 12 is installed on the pipeline connected to the first absorbent liquid outlet, and the circulating preheater 14 is installed on the pipeline connected to the first absorbent liquid outlet and the circulating liquid inlet.

[0073] This invention provides an apparatus for treating ammonia-containing tail gas using CO2, which assists in realizing the above-mentioned method of treating ammonia-containing tail gas using CO2. It utilizes CO2 and water to generate a carbonic acid solution, which effectively reduces the NH3 content in the ammonia-containing tail gas, and provides a pathway for returning the first absorbent liquid to participate in absorption and deammoniation, thus saving water consumption.

[0074] Furthermore, Figure 3 This is a schematic diagram of another device for treating ammonia-containing tail gas using CO2, provided by the present invention. Figure 3 As shown, the device also includes a second dissolution unit 2, which includes an undissolved CO2 inlet, a low-concentration CO2 outlet, an absorption portion inlet, and a second absorbent outlet; and the absorption portion inlet and the undissolved CO2 inlet are not arranged in the same direction; the dissolution unit also includes a CO2 outlet; wherein, the CO2 outlet is connected to the undissolved CO2 inlet, the first absorbent outlet is connected to the absorption portion inlet, and the second absorbent outlet is connected to the circulating liquid inlet.

[0075] The second dissolution unit 2 can further absorb undissolved CO2 in the absorption unit, further generating ammonium bicarbonate and / or ammonium carbonate solution. The generated ammonium bicarbonate and / or ammonium carbonate solution is further circulated through the second absorbent outlet and the circulating liquid inlet to participate in the absorption and removal of NH3 content in ammonia-containing tail gas, achieving a highly efficient ammonia removal effect.

[0076] It is understood that some of the CO2 introduced into the dissolving unit will not dissolve in the water. Therefore, in order to further utilize this undissolved CO2, the device provided by the present invention also includes a second dissolving unit 2. The present invention does not limit the form of the second dissolving unit 2, as long as it can provide the effect of further dissolving the undissolved CO2 in the first absorbent liquid.

[0077] Specifically, the second dissolving unit 2 includes at least an undissolved CO2 inlet, a low-concentration CO2 outlet, an absorption portion inlet, and a second absorbent outlet. The dissolving unit 3 also includes a CO2 outlet. It is understood that undissolved CO2 flows out of the dissolving unit through the CO2 outlet and then enters the second dissolving unit 2 through the undissolved CO2 inlet. Part of the first absorbent enters through the absorption portion inlet, and the second absorbent generated in the second dissolving unit is discharged through the second absorbent outlet. The CO2 that has been redissolved is directly discharged through the low-concentration CO2 outlet. Similarly, in order to achieve a sufficient contact dissolution effect, the absorption portion inlet and the undissolved CO2 inlet are not arranged in the same direction. For example, the absorption portion inlet can be located at the top of the second dissolving unit 2, and the undissolved CO2 inlet can be located at the bottom of the second dissolving unit 2.

[0078] Furthermore, the CO2 outlet is connected to the undissolved CO2 inlet. The undissolved CO2 exits the dissolution unit 3 through the CO2 outlet and then enters the second dissolution unit 2 through the undissolved CO2 inlet, where it is absorbed again to generate a carbonic acid solution. The first absorbent outlet is connected to the absorption section inlet. The first absorbent flows out of the absorption unit 1 through the first absorbent outlet and then enters the second dissolution unit 2 through the absorption section inlet to further dissolve the undissolved CO2. It can be understood that, in order to further treat ammonia-containing tail gas more efficiently and save water consumption, the second absorbent outlet is connected to the circulating liquid inlet, so that the second absorbent can flow out of the second dissolution unit 2 through the second absorbent outlet and then re-enter the absorption unit 1 through the circulating liquid inlet.

[0079] It is understandable that part of the first absorbent enters the second dissolving unit and part returns to the absorption unit. Since the first absorbent can also be directly used to produce by-products, the pipeline connected to the outlet of the first absorbent is also provided with an outlet connected to the outside.

[0080] In one specific implementation, such as Figure 4 As shown, the dissolution unit includes a primary scrubbing tower 03; the absorption unit includes an ammonia absorption tower 01; and the second dissolution unit includes a secondary scrubbing tower 02. The device utilizes CO2 to treat ammonia-containing tail gas through these towers, facilitating the efficient removal of NH3 from the tail gas while simultaneously preparing ammonium carbonate / ammonium bicarbonate and absorbing excess CO2.

[0081] Furthermore, such as Figure 4As shown, the device for treating ammonia-containing tail gas using CO2 includes: a dissolution unit, an absorption unit, and a second dissolution unit; the dissolution unit includes a primary scrubbing tower 03, a CO2 induced draft fan 15, and a primary discharge pump 16; wherein, the primary scrubbing tower 03 has a CO2 inlet at the bottom, a water inlet at the top, and a carbonic acid solution outlet at the bottom, and the primary scrubbing tower 03 is a packed tower; the absorption unit includes an ammonia absorption tower 01, an ammonia induced draft fan 11, an absorption tower product pump 12, and a circulating preheater 14; wherein, the ammonia absorption tower 01 has a carbonic acid solution inlet at the top, and the second dissolution unit is a packed tower. The reactor has an ammonia-containing tail gas inlet, an absorption tail gas outlet at the top of the tower, a first absorbent liquid outlet at the bottom, and circulating liquid inlets at the middle and lower sections. The upper section of the ammonia absorption tower 01 is a plate tower, and the middle and lower sections are packed towers. The second dissolution unit includes a two-stage washing tower 02, a booster pump 13, a two-stage discharge pump 17, and a feed preheater 18. The bottom of the two-stage washing tower 02 has an undissolved CO2 inlet, a low-concentration CO2 outlet at the top, an absorption section inlet at the top, and a second absorbent liquid outlet at the bottom. The two-stage washing tower 02 is a packed tower.

[0082] It is understood that the ammonia induced draft fan 11, the absorption tower product pump 12, the CO2 induced draft fan 15, the primary discharge pump 16, and the secondary discharge pump 17 provide power, pressurize, and ensure smooth flow of materials into the device. The booster pump 13, the circulating preheater 14, and the feed preheater 18 are used in conjunction with the method provided by this invention to further pressurize and heat the materials, which is beneficial for the efficient treatment of ammonia-containing tail gas.

[0083] Furthermore, such as Figure 4 As shown, the carbonic acid solution outlet is connected to the carbonic acid solution inlet, the first absorbent outlet is connected to the circulating liquid inlet, the CO2 outlet is connected to the undissolved CO2 inlet, the first absorbent outlet is connected to the absorption section inlet, and the second absorbent outlet is connected to the circulating liquid inlet.

[0084] CO2 induced draft fan 15 is installed on the pipeline connected to the CO2 inlet; primary discharge pump 16 is installed on the pipeline connected to the carbonate solution outlet and carbonate solution inlet; ammonia induced draft fan 11 is installed on the pipeline connected to the ammonia-containing tail gas inlet; absorber product pump 12 is installed on the pipeline connected to the first absorbent outlet; circulating preheater 14 is installed on the pipeline connected to the first absorbent outlet and circulating liquid inlet; booster pump 13 is installed on the pipeline connected to the first absorbent outlet and the absorption section inlet; secondary discharge pump 17 and feed preheater 18 are both installed on the pipeline connected to the second absorbent outlet and the circulating liquid inlet.

[0085] Furthermore, the present invention also provides a production system including the aforementioned device for treating ammonia-containing tail gas using CO2. In one specific embodiment, the emission outlet for ammonia-containing tail gas in the soda ash workshop can be directly connected to the ammonia-containing tail gas inlet, and the surplus CO2 in the plant can be directly connected to the CO2 inlet. This achieves the requirements for tail gas treatment and carbon emission reduction, contributing to the realization of the "dual carbon" goal, while also achieving cost reduction and efficiency improvement, demonstrating good green environmental protection value and application prospects.

[0086] The following detailed description of a method and apparatus for treating ammonia-containing tail gas using CO2, through specific embodiments, illustrates the present invention.

[0087] The ammonia-containing tail gas flow rate in the following examples is 1785 Nm³. 3 / h, of which the NH3 content is 1455mg / Nm 3 .

[0088] Example 1

[0089] The process method used in this embodiment is as follows: Figure 2 The apparatus shown performs the following steps:

[0090] (1) The excess CO2 in the plant is dissolved in water at a rate of 20 kg / h. After being pressurized to 1301 kPa by CO2 induced draft fan 15, it is sent to the CO2 inlet on the bottom of scrubbing tower 01. Water is fed directly to the water inlet at the top of scrubbing tower 01 at a rate of 12084 kg / h. The water is then evenly sprayed into the tower through a liquid distributor, where it flows countercurrently with CO2 and dissolves on the packing surface to generate a carbonic acid solution. The operating pressure of scrubbing tower 01 is 100 kPa, and the operating temperature is 40.1℃.

[0091] (2) The ammonia-containing tail gas is pressurized to 96.9 kPa by the ammonia induced draft fan 11 and then sent to the ammonia-containing tail gas inlet of the ammonia absorption tower 01. The operating pressure of the ammonia absorption tower 01 is 97 kPa and the operating temperature is 40.6℃. The carbonic acid solution is discharged from the carbonic acid solution outlet of the first-stage scrubbing tower 03, pressurized to 250 kPa by the first-stage discharge pump 16, and then sent to the carbonic acid solution inlet at the top of the ammonia absorption tower 01. It is then evenly sprayed into the tower by the liquid distributor and has a first counter-current contact with the ammonia-containing tail gas to generate the first absorbent liquid.

[0092] (3) The first absorbent generated in the ammonia absorption tower 01 is discharged from the bottom of the ammonia absorption tower 01 via the absorption tower product pump 12. It has two destinations: ① The first absorbent with a flow rate of 5000 kg / h is used as a circulating part and enters the circulating liquid inlet of the middle and lower sections of the ammonia absorption tower 01 after passing through the circulating heat exchanger 14, and participates in the first reverse contact in circulation; ② The remaining first absorbent is used as a product part and after passing through the buffer zone, the generated ammonium carbonate / ammonium bicarbonate is sent to the outside of the boundary zone.

[0093] The NH3 content in the treated ammonia-containing exhaust gas is less than 50 mg / Nm³. 3 .

[0094] Example 2

[0095] The process method used in this embodiment is as follows: Figure 4 The apparatus shown performs the following steps:

[0096] (1) The excess CO2 in the plant is dissolved in water at a rate of 510 kg / h. After being pressurized to 1301 kPa by the CO2 induced draft fan 15, the CO2 is sent to the CO2 inlet on the bottom of the primary scrubbing tower 03. Water is fed directly to the water inlet at the top of the primary scrubbing tower 03 at a rate of 5600 kg / h. The water is then evenly sprayed into the tower through a liquid distributor, where it flows countercurrently with the CO2 and dissolves on the packing surface to generate a carbonic acid solution. The operating pressure of the primary scrubbing tower 03 is 100 kPa, and the operating temperature is 40.1℃.

[0097] (2) The ammonia-containing tail gas is pressurized to 96.9 kPa by the ammonia induced draft fan 11 and then sent to the ammonia-containing tail gas inlet of the ammonia absorption tower 01. The operating pressure of the ammonia absorption tower 01 is 97 kPa and the operating temperature is 40.6℃. The carbonic acid solution is discharged from the carbonic acid solution outlet of the first-stage scrubbing tower 03, pressurized to 250 kPa by the first-stage discharge pump 16, and then sent to the carbonic acid solution inlet at the top of the ammonia absorption tower 01. It is then evenly sprayed into the tower by the liquid distributor and has a first counter-current contact with the ammonia-containing tail gas to generate the first absorbent liquid.

[0098] (3) The undissolved CO2 after being dissolved in the first-stage washing tower 03 is discharged from the CO2 outlet at the top of the first-stage washing tower 03 and directly enters the undissolved CO2 inlet of the bottom of the second-stage washing tower 02. The operating pressure of the second-stage washing tower 02 is 100 kPa and the operating temperature is 41.2℃.

[0099] (4) The first absorbent generated in the ammonia absorption tower 01 is discharged from the first absorbent outlet of the ammonia absorption tower 01 via the product pump 12. There are three destinations: ① The first absorbent with a flow rate of 770,000 kg / h is used as a circulation part. After passing through the circulation heat exchanger 14, it enters the circulation inlet of the middle and lower sections of the ammonia absorption tower 01 and participates in the first reverse contact. ② The first absorbent with a flow rate of 187,523 kg / h is used as an absorption part. After being pressurized to 101.3 kPa by the booster pump, it enters the absorption part inlet of the upper section of the secondary scrubbing tower 02 and undergoes a second reverse contact with the undissolved CO2 to generate the second absorbent. ③ The remaining first absorbent is used as a product part. After passing through the buffer zone, the generated ammonium carbonate / ammonium bicarbonate is sent to the outside of the zone.

[0100] (5) The second absorbent generated in the secondary scrubbing tower 02 is discharged from the second absorbent outlet at the bottom of the ammonia absorption tower 01. After being preheated to 40°C by the secondary discharge pump 17 and the feed preheater 18, it re-enters the circulating liquid inlet of the middle and lower sections of the ammonia absorption tower 01 and participates in the first reverse contact.

[0101] The NH3 content in the treated ammonia-containing exhaust gas is below 40 mg / Nm³. 3 .

[0102] Example 3

[0103] In step (1) of Example 2, the water flow rate is modified to 9700 kg / h.

[0104] In step (4) of Example 2, the water flow rate in the circulating section ① is modified to 13700 kg / h, and the water flow rate in the absorption section ② is modified to 586000 kg / h.

[0105] The remaining conditions are the same as in Example 2.

[0106] The NH3 content in the treated ammonia-containing waste gas was 49.3 mg / Nm³. 3 .

[0107] Comparative Example 1

[0108] The process method used in this comparative example is as follows: Figure 5 The apparatus shown includes an absorption unit.

[0109] The absorption unit includes an ammonia absorption tower 01, which is equipped with a water inlet, a water outlet, an ammonia-containing tail gas inlet, and a tail gas outlet after absorption. The water inlet and the ammonia-containing tail gas inlet are not in the same direction. The upper section of the ammonia absorption tower 01 is a plate tower and the lower section is a packed tower.

[0110] The treatment of ammonia-containing tail gas using the above-mentioned device includes the following steps:

[0111] The ammonia-containing tail gas is pressurized to 96.9 kPa by an ammonia induced draft fan and then sent to the ammonia tail gas inlet at the bottom of the ammonia absorption tower. The operating pressure of the ammonia absorption tower is 97 kPa, and the operating temperature is 40.6℃. Water is fed directly to the water inlet at the top of the ammonia absorption tower at a rate of 15120 kg / h, and then evenly sprayed into the tower through a liquid distributor, flowing countercurrently with the ammonia tail gas for absorption.

[0112] The NH3 content in the treated ammonia-containing exhaust gas was 98.5 mg / Nm³. 3 .

[0113] Comparative Example 2

[0114] In step (3) of Example 1, the flow rate of the first absorbent in step ① is modified to 3500 kg / h, so that it can circulate and participate in the first reverse contact.

[0115] The remaining conditions are the same as in Example 1.

[0116] The NH3 content in the treated ammonia-containing exhaust gas was 74.9 mg / Nm³. 3 .

[0117] Comparative Example 3

[0118] In step (1) of Example 2, the amount of CO2 dissolved in water is modified to 10 kg / h.

[0119] The remaining conditions are the same as in Example 2.

[0120] The NH3 content in the treated ammonia-containing exhaust gas was 67.8 mg / Nm³. 3 hour.

[0121] Comparative Example 4

[0122] In step (1) of Example 2, the water flow rate is modified to 4000 kg / h.

[0123] The remaining conditions are the same as in Example 2.

[0124] The NH3 content in the treated ammonia-containing exhaust gas was 63.4 mg / Nm³. 3 .

[0125] As can be seen from Examples 1-3, this invention utilizes CO2 to absorb NH3 from ammonia-containing tail gas to prepare ammonium bicarbonate and / or ammonium carbonate, thereby effectively reducing the NH3 content in the ammonia-containing tail gas. Furthermore, by circulating the ammonium bicarbonate and / or ammonium carbonate solution to participate in rinsing and removing NH3, water consumption is saved, resulting in an NH3 content in the treated tail gas below 50 mg / Nm³. 3 This method achieves national emission standards by venting the wastewater through high-point venting, effectively reducing carbon emissions during production, making reasonable use of surplus CO2 within the plant area, and producing ammonium carbonate and / or ammonium bicarbonate products, thus achieving cost reduction and efficiency improvement. In contrast, Comparative Example 1 uses direct water absorption for ammonia removal, and Comparative Example 2 uses most of the first absorbent liquid for producing ammonium carbonate and / or ammonium bicarbonate products, with too small a proportion participating in the recycling process. Even with comparable water usage, these methods fail to meet national emission standards. Furthermore, the raw materials introduced in Comparative Examples 3 and 4 do not meet the scope defined in this invention, ultimately failing to meet national emission standards.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for treating ammonia-containing tail gas using CO2, characterized in that, Includes the following steps: CO2 is dissolved in water to obtain a carbonic acid solution; The carbonated solution is brought into a first counter-current contact with the ammonia-containing tail gas to be treated to obtain a first absorbent liquid and the absorbed tail gas, and the absorbed tail gas is then discharged. At least a portion of the first absorbent liquid is circulated to participate in the first reverse contact; The first absorbent liquid includes a circulation section and an absorption section, wherein the circulation section cyclically participates in the first reverse contact; The absorption section undergoes a second counter-current contact with the undissolved CO2 in the dissolution process to obtain a second absorbent liquid; the second absorbent liquid circulates and participates in the first counter-current contact; the flow rate ratio of the circulation section to the absorption section is (0.17~0.24):1; The ratio of the NH3 content in the ammonia-containing tail gas, the mass of CO2 dissolved in water per unit time, the mass of water per unit time, and the mass of the first absorbent circulating in the first reverse contact per unit time is (500~1800):(15~750):(5600~15500):(140000~1200000). The NH3 content in the exhaust gas after absorption is less than 50 mg / Nm³. 3 .

2. The method according to claim 1, characterized in that, The first absorbent liquid also includes a product portion; the flow rate ratio of the circulation portion, the absorption portion and the product portion is (12~27):(58~114):(1~3).

3. The method according to claim 2, characterized in that, The product is partially processed by CO2 concentration, crystallization and drying to obtain ammonium bicarbonate and / or ammonium carbonate products.

4. The method according to any one of claims 1-3, characterized in that, The CO2 is pressurized to 1236-1366 kPa and then dissolved in water; wherein the dissolution treatment is performed at a pressure of 95-105 kPa and a temperature of 35-45°C; and / or, The ammonia-containing tail gas is pressurized to 95-105 kPa and then subjected to the first reverse contact with the carbonic acid solution. The pressure of the first reverse contact is 95-105 kPa, and the temperature is 35-45°C; and / or, The pressure of the second reverse contact is 95-105 kPa, and the temperature is 35-45℃.

5. A device for treating ammonia-containing tail gas using CO2, characterized in that, The apparatus is used to perform the method according to any one of claims 1-4; the apparatus includes a dissolving unit and an absorption unit, the dissolving unit including a CO2 inlet, a water inlet and a carbonic acid solution outlet; The absorption unit includes a carbonic acid solution inlet, an ammonia-containing tail gas inlet, an absorbed tail gas outlet, a first absorbent liquid outlet, and a circulating liquid inlet, and the carbonic acid solution inlet and the ammonia-containing tail gas inlet are not arranged in the same direction. The carbonate solution outlet is connected to the carbonate solution inlet, and the first absorbent liquid outlet is connected to the circulating liquid inlet. It also includes a second dissolution unit, which includes an undissolved CO2 inlet, a low-concentration CO2 outlet, an absorption portion inlet, and a second absorbent outlet; and the absorption portion inlet and the undissolved CO2 inlet are not arranged in the same direction; the dissolution unit also includes a CO2 outlet; The CO2 outlet is connected to the undissolved CO2 inlet, the first absorbent outlet is connected to the absorbent portion inlet, and the second absorbent outlet is connected to the circulating liquid inlet.

6. The apparatus according to claim 5, characterized in that, The dissolution unit includes a washing tower; the absorption unit includes an ammonia absorption tower; and the second dissolution unit includes a washing tower.

7. A production system, characterized in that, Includes the apparatus described in claim 5 or 6.

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