Method and device for capturing and fixing carbon dioxide in ship tail gas

Abstract

The invention relates to the technical field of carbon dioxide separation, and discloses a method and a device for capturing and fixing carbon dioxide in ship tail gas. The method comprises the following steps: introducing seawater, an amine catalyst and ship tail gas into a CO2 trapping tower to complete CO2 absorption reaction, and discharging decarburized tail gas and a mixed solution I; introducing the mixed solution I into a CO2 immobilization reactor, carrying out solid-liquid separation after completing a CO2 immobilization precipitation reaction, and discharging a CO2 immobilization product and a mixed solution II; the mixed solution II is introduced into a catalyst regenerator, after a catalyst regeneration reaction is completed, solid-liquid separation is carried out, a CO2 fixed product and a mixed solution III are discharged, and the mixed solution III is concentrated and reused in S1. By adopting the method disclosed by the invention, the regeneration energy consumption of the amine catalyst can be reduced, and the CO2 is directly fixed to form a solid-phase product after being captured, so that the subsequent processes of compressing, liquefying and storing the CO2 in a storage tank can be omitted, and the occupied area of the device is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide separation, and particularly to a method and device for capturing and fixing carbon dioxide in ship exhaust gas. Background Art

[0002] The shipping industry is an important source of carbon dioxide emissions, especially ocean-going ships that mainly consume fossil fuels such as heavy oil. Capturing carbon dioxide from ship exhaust gas is an important carbon emission reduction technology. At present, chemical absorption process routes are mostly used for capturing carbon dioxide from ship exhaust gas. This technology uses alkaline absorbents to undergo acid-base neutralization reactions with carbon dioxide, thereby separating carbon dioxide in ship exhaust gas. According to whether the alkaline absorbent is recycled in the carbon dioxide capture process, the carbon dioxide capture process can be divided into a cyclic absorption process and a non-cyclic absorption process.

[0003] The non-cyclic absorption process generally uses strong alkaline absorbents to undergo irreversible reactions with CO2 in ship exhaust gas. Since the absorbent is not renewable, it will result in a relatively high cost for carbon capture from ship exhaust gas. In comparison, renewable weak alkaline organic amine absorbents are usually used in the cyclic absorption process to undergo reversible reactions with CO2, and then carbon dioxide can be desorbed by heating to realize the regeneration of the absorbent (for example, patent CN113828120A). This method can reduce the absorbent cost, but there are problems such as high energy consumption for absorbent regeneration, and the captured carbon dioxide is not fixed. The separated gaseous carbon dioxide needs to be compressed, liquefied, and stored using additional equipment, resulting in a relatively large floor area for the entire device, which limits the application of this carbon dioxide capture process on ships. Summary of the Invention

[0004] In order to solve the above technical problems, that is, in the existing carbon dioxide cyclic absorption process, there are high energy consumption for absorbent regeneration, the captured carbon dioxide is not fixed, and additional CO2 compression and liquefaction devices and CO2 storage tanks need to be added. The present invention provides a method and device for capturing and fixing carbon dioxide in ship exhaust gas. By using the method of the present invention, the energy consumption for regenerating the amine catalyst can be reduced, and the CO2 is directly fixed to form a solid-phase product after capture, which can eliminate the subsequent processes of CO2 compression, liquefaction, and storage in a tank, thereby reducing the floor area of the device.

[0005] The specific technical solution of the present invention is as follows: In the first aspect, the present invention provides a method for capturing and fixing carbon dioxide in ship exhaust gas, including the following steps: S1: Pass seawater, an amine catalyst, and ship exhaust gas into a CO2 capture tower to complete the CO2 absorption reaction, and discharge the decarbonized exhaust gas and mixture I; the CO2 absorption reaction includes: , , , Among them, CA is an amine catalyst; S2: Feed the mixture I into a CO2 fixation reactor. After completing the CO2 fixation precipitation reaction, perform solid-liquid separation, and discharge the CO2 fixation product and mixture II; The CO2 fixation precipitation reaction includes: , ; S3: Feed the mixture II into a catalyst regenerator. After completing the catalyst regeneration reaction, perform solid-liquid separation, and discharge the CO2 fixation product and mixture III. After concentrating mixture III, recycle it to S1; The catalyst regeneration reaction includes: , .

[0006] The principle of carbon dioxide capture and fixation in the present invention is as follows: (1) First, under the action of an amine catalyst, CO2 is absorbed by the mixture of seawater and the amine catalyst through a CO2 absorption reaction. The specific CO2 absorption reaction is as follows: ; ; .

[0007] (2) Under the action of calcium ions and magnesium ions in seawater, the CO3 formed after CO2 is absorbed by the mixture of seawater and the amine catalyst 2− undergoes a CO2 fixation precipitation reaction and is converted into a precipitate. The specific CO2 fixation precipitation reaction is as follows: ; .

[0008] (3) Through the catalyst regeneration reaction, the amine catalyst after absorbing CO2 can be regenerated. At the same time, the released carbon-containing substances precipitate under the action of calcium ions and magnesium ions in seawater. The specific catalyst regeneration reaction is as follows: ; .

[0009] In the above process, the CO2 absorption reaction is completed in the CO2 capture tower. At the same time, a partial CO2 fixation precipitation reaction also occurs in the CO2 capture tower; in the CO2 fixation reactor, the CO2 fixation precipitation reaction is completed, and a partial catalyst regeneration reaction occurs simultaneously. The CO2 fixation products (CaCO3 and MgCO3) can be separated by solid-liquid separation; in the catalyst regenerator, the catalyst regeneration reaction is completed, and the CO2 fixation products (CaCO3 and MgCO3) can be separated by solid-liquid separation.

[0010] In the above way, the present invention can directly use seawater to capture and fix carbon dioxide in ship exhaust gas, without consuming fresh water on the ship or undergoing a complex seawater desalination process; moreover, after being captured, the CO2 is directly fixed to form solid-phase products (CaCO3 and MgCO3), which can eliminate the subsequent processes of CO2 compression, liquefaction, and storage in tanks, thus reducing the floor area of the entire device and lowering energy consumption, especially suitable for ship conditions; in addition, through the process of the present invention, the recycling of amine catalysts can be realized, enabling the entire device to operate in a long cycle, reducing the catalyst cost, and the present invention uses calcium ions and magnesium ions in seawater to regenerate the amine catalyst, which can reduce the energy consumption for catalyst regeneration.

[0011] In addition, the present invention separates the CO2 absorption reaction, the CO2 fixation precipitation reaction, and the catalyst regeneration reaction in three reaction devices (CO2 capture tower, CO2 fixation reactor, catalyst regenerator). This design has the following effects: The CO2 absorption reaction is an exothermic reaction, which easily causes the temperature in the CO2 capture tower to rise, and the temperature at the upper part of the CO2 capture tower may reach a relatively high level. Separating the CO2 fixation precipitation reaction and the catalyst regeneration reaction from the CO2 absorption reaction in different devices is conducive to controlling the temperature during the CO2 fixation precipitation reaction and the catalyst regeneration reaction, thereby promoting the progress of these two reactions.

[0012] Preferably, in step S1, the amine catalyst is one of the following a) or b): a) Comprising diethylenetriamine and 2,2,6,6-tetramethylpiperidine with a mass ratio of 1:0.0033 - 0.2; b) Comprising 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol with a mass ratio of 1:0.15 - 1.6.

[0013] Both of the above a) and b) amine catalysts are liquid-phase catalysts, which can achieve homogeneous catalysis and have a high CO2 capture efficiency. Moreover, in the two amine catalysts of a) and b), two specific components are respectively compounded, and under the ratio of the present invention, they can produce a synergistic effect and improve the catalytic effect. The specific mechanism is as follows: In a), by compounding diethylenetriamine and 2,2,6,6 - tetramethylpiperidine in a mass ratio of 1:0.0033 - 0.2, a relatively high CO2 capture efficiency can be achieved by using diethylenetriamine. At the same time, the stability of both can be improved through the conjugation effect and steric effect between diethylenetriamine and 2,2,6,6 - tetramethylpiperidine. In this way, a relatively high CO2 capture efficiency can be realized, and during long - term operation, the degradation loss of amine catalysts can be reduced.

[0014] In b), by compounding 2 - amino - 2 - methyl - 1 - propanol and 1 - methyl - 4 - piperidinol in a mass ratio of 1:0.15 - 1.6, the intermolecular hydrogen - bond interaction formed between these two components can be utilized to reduce the volatilization loss of 2 - amino - 2 - methyl - 1 - propanol. At the same time, 1 - methyl - 4 - piperidinol can provide hydrogen protons for the reaction between 2 - amino - 2 - methyl - 1 - propanol and CO2, thereby improving the CO2 capture efficiency. In this way, 2 - amino - 2 - methyl - 1 - propanol and 1 - methyl - 4 - piperidinol can synergistically improve the CO2 capture efficiency and reduce the loss of amine catalysts during long - term operation.

[0015] Preferably, in step S1, the CO2 capture tower is a packed tower, a plate tower, or a hollow - fiber membrane contactor.

[0016] Preferably, in step S1, the operating temperature of the CO2 capture tower is 20 - 80°C.

[0017] Preferably, in step S2, the operating temperature of the CO2 fixation reactor is 20 - 50°C.

[0018] Preferably, in step S3, the operating temperature of the catalyst regenerator is 20 - 50°C.

[0019] Preferably, in step S1, the specific process of introducing seawater, amine catalyst, and ship exhaust gas into the CO2 capture tower includes: mixing seawater and amine catalyst in a mass ratio of 1:0.05 - 4, introducing the obtained mixture of seawater and amine catalyst into the CO2 capture tower, and simultaneously introducing ship exhaust gas into the CO2 capture tower.

[0020] Preferably, in step S1, the flow rates of the mixture of seawater and amine catalyst and ship exhaust gas introduced into the CO2 capture tower are 15 - 30 m 3 / h and 4000 - 6000 m 3 / h, the flow rate of the ship's exhaust gas in the CO2 capture tower is 1 - 3 m / s, and the residence time of the mixture of seawater and amine catalyst in the CO2 capture tower is 5 - 45 min (i.e., after being introduced into the CO2 capture tower, it stays for 5 - 45 min before being discharged); in step S2, the residence time of the mixed liquid I in the CO2 fixation reactor is 0 - 20 min (i.e., after being introduced into the CO2 fixation reactor, it stays for 0 - 20 min before being discharged); in step S3, the residence time of the mixed liquid II in the catalyst regenerator is 30 - 120 min (i.e., after being introduced into the catalyst regenerator, it stays for 30 - 120 min before being discharged).

[0021] Preferably, in step S3, after concentrating the mixed liquid III to an amine catalyst content of not less than 85 wt%, it is recycled to S1.

[0022] In a second aspect, the present invention provides an apparatus for capturing and fixing carbon dioxide in ship exhaust gas using the above method, comprising a mixing tank, a CO2 capture tower, a CO2 fixation reactor, and a catalyst regenerator connected in sequence; a seawater inlet and a catalyst inlet are provided in the mixing tank; a ship exhaust gas inlet and a decarbonized exhaust gas outlet are provided in the CO2 capture tower; a solid-liquid separator and a CO2 fixation product outlet are provided in the CO2 fixation reactor and the catalyst regenerator; the catalyst regenerator is connected to the mixing tank.

[0023] Compared with the prior art, the present invention has the following advantages: (1) By using the method and apparatus of the present invention, the CO2 in the ship exhaust gas can be directly captured and fixed using seawater, without consuming the fresh water resources on the ship or pre-complex desalination of seawater.

[0024] (2) By using the method and apparatus of the present invention, the captured CO2 can be fixed to form a solid-phase product, without the need to additionally set up CO2 compression, liquefaction devices, and CO2 storage tanks, thus reducing the floor area of the apparatus and the energy consumption of the apparatus.

[0025] (3) In the method and apparatus of the present invention, the regeneration of the amine catalyst is achieved by using Ca 2+ and Mg 2+ in seawater, which can reduce the energy consumption of catalyst regeneration. Description of the Drawings

[0026] Figure 1 It is a flowchart for capturing and fixing carbon dioxide in ship exhaust gas in Example 1.

[0027] Figure 2 It is a flowchart for capturing carbon dioxide in ship exhaust gas in Comparative Example 1.

[0028] Figure 3It is a flow chart for capturing carbon dioxide in the exhaust gas of ships in Comparative Example 2. Detailed implementation manners

[0029] The present invention will be further described below in conjunction with embodiments.

[0030] First, the present invention relates to a method for capturing and fixing carbon dioxide in ship exhaust gas, including the following steps: S1: Introduce seawater, amine catalyst and ship exhaust gas into the CO2 capture tower to complete the CO2 absorption reaction, and discharge the decarbonized exhaust gas and mixture I; the CO2 absorption reaction includes: , , , wherein, CA is an amine catalyst; S2: Introduce mixture I into the CO2 fixation reactor. After completing the CO2 fixation precipitation reaction, perform solid-liquid separation, and discharge the CO2 fixation product and mixture II; the CO2 fixation precipitation reaction includes: , ; S3: Introduce mixture II into the catalyst regenerator. After completing the catalyst regeneration reaction, perform solid-liquid separation, and discharge the CO2 fixation product and mixture III. After concentrating mixture III, recycle it to S1; the catalyst regeneration reaction includes: , .

[0031] In some specific implementation manners, in step S3, after concentrating mixture III to a content of amine catalyst not less than 85 wt%, recycle it to S1.

[0032] In some specific implementation manners, in step S1, the amine catalyst is the following a) or b): a) Containing diethylenetriamine and 2,2,6,6-tetramethylpiperidine with a mass ratio of 1:0.0033 - 0.2; b) Containing 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol with a mass ratio of 1:0.15 - 1.6.

[0033] In some specific embodiments, in step S1, the specific process of introducing seawater, amine catalyst, and ship exhaust gas into the CO2 capture tower includes: mixing seawater and amine catalyst with a mass ratio of 1:0.05 - 4, introducing the obtained mixture of seawater and amine catalyst into the CO2 capture tower, and simultaneously introducing ship exhaust gas into the CO2 capture tower; the flow rates of the mixture of seawater and amine catalyst and ship exhaust gas introduced into the CO2 capture tower are 15 - 30 m 3 / h and 4000 - 6000 m 3 / h respectively, the flow velocity of the ship exhaust gas in the CO2 capture tower is 1 - 3 m / s, and the residence time of the mixture of seawater and amine catalyst in the CO2 capture tower is 5 - 45 min.

[0034] In some specific embodiments, in step S1, the CO2 capture tower is a packed tower, a plate tower, or a hollow fiber membrane contactor.

[0035] In some specific embodiments, in step S1, the operating temperature of the CO2 capture tower is 20 - 80°C.

[0036] In some specific embodiments, in step S2, the operating temperature of the CO2 fixation reactor is 20 - 50°C, and the residence time of the mixture I in the CO2 fixation reactor is 0 - 20 min.

[0037] In some specific embodiments, in step S3, the operating temperature of the catalyst regenerator is 20 - 50°C, and the residence time of the mixture II in the catalyst regenerator is 30 - 120 min.

[0038] Second, the present invention relates to a device for capturing and fixing carbon dioxide in ship exhaust gas by using the above method, including a mixing tank, a CO2 capture tower, a CO2 fixation reactor, and a catalyst regenerator connected in sequence; the mixing tank is provided with a seawater inlet and a catalyst inlet; the CO2 capture tower is provided with a ship exhaust gas inlet and a decarbonized exhaust gas outlet; the CO2 fixation reactor and the catalyst regenerator are provided with a solid-liquid separator and a CO2 fixation product outlet; the catalyst regenerator is connected to the mixing tank.

[0039] The present invention will be described below through specific examples. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, the changes and advantages that can be conceived by those skilled in the art are included in the present invention, and the protection scope of the present invention is defined by the appended claims and any equivalents thereof.

[0040] Example 1 The carbon dioxide capture and fixation device for ship exhaust gas in this embodiment consists of a mixing tank, a CO2 capture tower, a CO2 fixation reactor, and a catalyst regenerator connected in sequence. The catalyst regenerator is connected to the mixing tank. The mixing tank is provided with a seawater inlet and a catalyst inlet. The CO2 capture tower is provided with a ship exhaust gas inlet and a decarbonized exhaust gas outlet. The CO2 fixation reactor and the catalyst regenerator are provided with a solid-liquid separator and a CO2 fixation product outlet. Using this device to capture and fix carbon dioxide in ship exhaust gas, the process is as Figure 1 shown, and the specific steps are as follows: S1: Introduce seawater and an amine catalyst into the mixing tank for mixing to obtain a seawater / amine catalyst mixture, where the content of the amine catalyst is 30 wt%, and the amine catalyst is a two-component catalyst composed of diethylenetriamine and 2,2,6,6-tetramethylpiperidine with a mass ratio of 1:0.0033.

[0041] S2: Feed the seawater / amine catalyst mixture and ship exhaust gas into the CO2 capture tower at flow rates of 25 m 3 / h and 5000 m 3 / h respectively. The operating temperature of the CO2 capture tower is 40 °C, the flow rate of the ship exhaust gas in the CO2 capture tower is 1 m / s, and the residence time of the seawater / amine catalyst mixture in the CO2 capture tower is 15 min. In the CO2 capture tower, the CO2 absorption reaction can be completed, and at the same time, a partial CO2 fixation precipitation reaction occurs. The decarbonized exhaust gas and mixture I are discharged from the CO2 capture tower.

[0042] S3: Feed the mixture I discharged from the CO2 capture tower into the CO2 fixation reactor. The operating temperature of the CO2 fixation reactor is 50 °C, and the residence time of the mixture I in the CO2 fixation reactor is 5 min. In the CO2 fixation reactor, the CO2 fixation precipitation reaction can be completed, and at the same time, a partial catalyst regeneration reaction occurs. Solid-liquid separation is carried out at the outlet of the CO2 fixation reactor to separate the CO2 fixation products (CaCO3 and MgCO3), and the remaining mixture II is discharged.

[0043] S4: Feed the mixture II into the catalyst regenerator. The operating temperature of the catalyst regenerator is 50 °C, and the residence time of the mixture II in the catalyst regenerator is 60 min. In the catalyst regenerator, the catalyst regeneration reaction can be completed. Solid-liquid separation is carried out at the outlet of the catalyst regenerator to separate the CO2 fixation products (CaCO3 and MgCO3), and the mixture III is discharged. After concentrating the mixture III to a content of 90 wt% of the amine catalyst, it is fed into the mixing tank for reuse to achieve the recycling of the amine catalyst.

[0044] Example 2 The carbon dioxide capture and fixation device for ship exhaust gas in this embodiment is the same as that in Embodiment 1. Using this device, the carbon dioxide in the ship exhaust gas is captured and fixed, and the process is as follows Figure 1 as shown, and the specific steps are as follows: S1: Seawater and an amine catalyst are introduced into a mixing tank for mixing to obtain a seawater / amine catalyst mixture, where the content of the amine catalyst is 30 wt%, and the amine catalyst is a two-component catalyst composed of diethylenetriamine and 2,2,6,6-tetramethylpiperidine with a mass ratio of 1:0.2.

[0045] S2: The seawater / amine catalyst mixture and the ship exhaust gas are respectively introduced into the CO2 capture tower at flow rates of 25 m 3 / h and 5000 m 3 / h. The operating temperature of the CO2 capture tower is 40 °C, the flow rate of the ship exhaust gas in the CO2 capture tower is 1 m / s, and the residence time of the seawater / amine catalyst mixture in the CO2 capture tower is 15 min. In the CO2 capture tower, the CO2 absorption reaction can be completed, and at the same time, a partial CO2 fixation precipitation reaction is carried out. The decarbonized exhaust gas and the mixed liquid I are discharged from the CO2 capture tower.

[0046] S3: The mixed liquid I discharged from the CO2 capture tower is introduced into the CO2 fixation reactor. The operating temperature of the CO2 fixation reactor is 50 °C, and the residence time of the mixed liquid I in the CO2 fixation reactor is 5 min. In the CO2 fixation reactor, the CO2 fixation precipitation reaction can be completed, and at the same time, a partial catalyst regeneration reaction is carried out. Solid-liquid separation is carried out at the outlet of the CO2 fixation reactor to separate the CO2 fixation products (CaCO3 and MgCO3), and the remaining mixed liquid II is discharged.

[0047] S4: The mixed liquid II is introduced into the catalyst regenerator. The operating temperature of the catalyst regenerator is 50 °C, and the residence time of the mixed liquid II in the catalyst regenerator is 60 min. In the catalyst regenerator, the catalyst regeneration reaction can be completed. Solid-liquid separation is carried out at the outlet of the catalyst regenerator to separate the CO2 fixation products (CaCO3 and MgCO3), and the mixed liquid III is discharged. After the mixed liquid III is concentrated to an amine catalyst content of 90 wt%, it is introduced into the mixing tank for reuse to realize the recycling of the amine catalyst.

[0048] Embodiment 3 The carbon dioxide capture and fixation device for ship exhaust gas in this embodiment is the same as that in Embodiment 1. Using this device, the carbon dioxide in the ship exhaust gas is captured and fixed, and the process is as follows Figure 1 as shown, and the specific steps are as follows: S1: Feed seawater and an amine catalyst into a mixing tank for mixing to obtain a seawater / amine catalyst mixture, where the content of the amine catalyst is 30 wt%, and the amine catalyst is a two-component catalyst composed of 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol with a mass ratio of 1:0.15.

[0049] S2: Feed the seawater / amine catalyst mixture and ship exhaust gas into a CO2 capture tower at flow rates of 25 m 3 / h and 5000 m 3 / h respectively. The operating temperature of the CO2 capture tower is 40 °C, the flow rate of the ship exhaust gas in the CO2 capture tower is 1 m / s, and the residence time of the seawater / amine catalyst mixture in the CO2 capture tower is 15 min. In the CO2 capture tower, the CO2 absorption reaction can be completed, and at the same time, a partial CO2 fixation precipitation reaction occurs. Decarbonized exhaust gas and mixture I are discharged from the CO2 capture tower.

[0050] S3: Feed mixture I discharged from the CO2 capture tower into a CO2 fixation reactor. The operating temperature of the CO2 fixation reactor is 50 °C, and the residence time of mixture I in the CO2 fixation reactor is 5 min. In the CO2 fixation reactor, the CO2 fixation precipitation reaction can be completed, and at the same time, a partial catalyst regeneration reaction occurs. Solid-liquid separation is carried out at the outlet of the CO2 fixation reactor to separate the CO2 fixation products (CaCO3 and MgCO3), and the remaining mixture II is discharged.

[0051] S4: Feed mixture II into a catalyst regenerator. The operating temperature of the catalyst regenerator is 50 °C, and the residence time of mixture II in the catalyst regenerator is 60 min. In the catalyst regenerator, the catalyst regeneration reaction can be completed. Solid-liquid separation is carried out at the outlet of the catalyst regenerator to separate the CO2 fixation products (CaCO3 and MgCO3), and mixture III is discharged. After concentrating mixture III to an amine catalyst content of 90 wt%, it is fed into the mixing tank for reuse to achieve the recycling of the amine catalyst.

[0052] Example 4 The carbon dioxide capture and fixation device for ship exhaust gas in this example is the same as that in Example 1. Using this device, carbon dioxide in ship exhaust gas is captured and fixed, and the process is as Figure 1 shown. The specific steps are as follows: S1: Feed seawater and an amine catalyst into a mixing tank for mixing to obtain a seawater / amine catalyst mixture, where the content of the amine catalyst is 30 wt%, and the amine catalyst is a two-component catalyst composed of 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol with a mass ratio of 1:1.6.

[0053] S2: Feed the seawater / amine catalyst mixture and ship exhaust gas into the CO2 capture tower at flow rates of 25 m 3 / h and 5000 m 3 / h respectively. The operating temperature of the CO2 capture tower is 40 °C. The flow rate of the ship exhaust gas in the CO2 capture tower is 1 m / s, and the residence time of the seawater / amine catalyst mixture in the CO2 capture tower is 15 min. Inside the CO2 capture tower, the CO2 absorption reaction can be completed, and at the same time, part of the CO2 fixation precipitation reaction occurs. Discharge the decarbonized exhaust gas and mixture I from the CO2 capture tower.

[0054] S3: Feed mixture I discharged from the CO2 capture tower into the CO2 fixation reactor. The operating temperature of the CO2 fixation reactor is 50 °C, and the residence time of mixture I in the CO2 fixation reactor is 5 min. Inside the CO2 fixation reactor, the CO2 fixation precipitation reaction can be completed, and at the same time, part of the catalyst regeneration reaction occurs. Perform solid-liquid separation at the outlet of the CO2 fixation reactor to separate the CO2 fixation products (CaCO3 and MgCO3), and discharge the remaining mixture II.

[0055] S4: Feed mixture II into the catalyst regenerator. The operating temperature of the catalyst regenerator is 50 °C, and the residence time of mixture II in the catalyst regenerator is 60 min. Inside the catalyst regenerator, the catalyst regeneration reaction can be completed. Perform solid-liquid separation at the outlet of the catalyst regenerator to separate the CO2 fixation products (CaCO3 and MgCO3), and discharge mixture III. After concentrating mixture III to an amine catalyst content of 90 wt%, feed it into the mixing tank for reuse to achieve the recycling of the amine catalyst.

[0056] Comparative Example 1 In this comparative example, the carbon dioxide capture process in ship exhaust gas is as Figure 2 shown, where: the absorbent used is a 30 wt% monoethanolamine (MEA) solution (the solvent is deionized water), and the residence time in the CO2 capture tower is 15 min; the flow rate of the ship exhaust gas fed into the CO2 capture tower is 5000 m 3 / h, and the flow rate in the CO2 capture tower is 1 m / s; the operating temperature of the CO2 capture tower is 40 °C, and the temperature of the CO2 desorption tower is 100 °C.

[0057] Comparative Example 2 In this comparative example, the carbon dioxide capture process in ship exhaust gas is as Figure 3As shown in the figure, where the total salt concentration of seawater is 3.5 wt%, and the total salt concentration of concentrated seawater is 7 wt%; the concentration of the sodium hydroxide solution obtained by bipolar membrane electrodialysis is 1 mol / L, and the residence time in the CO2 capture tower is 15 min; the flow rate of ship exhaust gas into the CO2 capture tower is 5000 m 3 / h, and the flow velocity in the CO2 capture tower is 1 m / s; the operating temperature of the CO2 capture tower is 40°C.

[0058] Comparative Example 3 The carbon dioxide capture and fixation device for ship exhaust gas in this comparative example is the same as that in Example 1. Using this device, the carbon dioxide in ship exhaust gas is captured and fixed, and the process is as Figure 1 shown, and the specific steps are as follows: S1: Seawater and diethylenetriamine (as an amine catalyst) are introduced into a mixing tank for mixing to obtain a seawater / diethylenetriamine mixture, where the content of diethylenetriamine is 30 wt%.

[0059] S2: The seawater / diethylenetriamine mixture and ship exhaust gas are respectively introduced into the CO2 capture tower at flow rates of 25 m 3 / h and 5000 m 3 / h. The operating temperature of the CO2 capture tower is 40°C, the flow velocity of ship exhaust gas in the CO2 capture tower is 1 m / s, and the residence time of the seawater / diethylenetriamine mixture in the CO2 capture tower is 15 min. In the CO2 capture tower, the CO2 absorption reaction can be completed, and at the same time, part of the CO2 fixation precipitation reaction occurs. Decarbonized exhaust gas and mixture I are discharged from the CO2 capture tower.

[0060] S3: The mixture I discharged from the CO2 capture tower is introduced into a CO2 fixation reactor. The operating temperature of the CO2 fixation reactor is 50°C, and the residence time of mixture I in the CO2 fixation reactor is 5 min. In the CO2 fixation reactor, the CO2 fixation precipitation reaction can be completed, and at the same time, part of the catalyst regeneration reaction occurs. Solid-liquid separation is carried out at the outlet of the CO2 fixation reactor to separate the CO2 fixation products (CaCO3 and MgCO3), and the remaining mixture II is discharged.

[0061] S4: The mixture II is introduced into a catalyst regenerator. The operating temperature of the catalyst regenerator is 50°C, and the residence time of mixture II in the catalyst regenerator is 60 min. In the catalyst regenerator, the catalyst regeneration reaction can be completed. Solid-liquid separation is carried out at the outlet of the catalyst regenerator to separate the CO2 fixation products (CaCO3 and MgCO3), and mixture III is discharged. After concentrating mixture III to an amine catalyst content of 90 wt%, it is introduced into the mixing tank for reuse to realize the recycling of the amine catalyst.

[0062] Comparative Example 4 The carbon dioxide capture and fixation device for ship exhaust gas in this comparative example is the same as that in Example 1. Using this device, the carbon dioxide in the ship exhaust gas is captured and fixed, and the process is as follows Figure 1 shown, and the specific steps are as follows: S1: Seawater and 2,2,6,6 - tetramethylpiperidine (as an amine catalyst) are introduced into a mixing tank for mixing to obtain a seawater / 2,2,6,6 - tetramethylpiperidine mixture, where the content of 2,2,6,6 - tetramethylpiperidine is 30 wt%.

[0063] S2: The seawater / 2,2,6,6 - tetramethylpiperidine mixture and the ship exhaust gas are respectively introduced into the CO2 capture tower at flow rates of 25 m 3 / h and 5000 m 3 / h. The operating temperature of the CO2 capture tower is 40°C, the flow rate of the ship exhaust gas in the CO2 capture tower is 1 m / s, and the residence time of the seawater / 2,2,6,6 - tetramethylpiperidine mixture in the CO2 capture tower is 15 min. In the CO2 capture tower, the CO2 absorption reaction can be completed, and at the same time, a partial CO2 fixation precipitation reaction occurs. The decarbonized exhaust gas and mixture I are discharged from the CO2 capture tower.

[0064] S3: The mixture I discharged from the CO2 capture tower is introduced into the CO2 fixation reactor. The operating temperature of the CO2 fixation reactor is 50°C, and the residence time of the mixture I in the CO2 fixation reactor is 5 min. In the CO2 fixation reactor, the CO2 fixation precipitation reaction can be completed, and at the same time, a partial catalyst regeneration reaction occurs. Solid - liquid separation is carried out at the outlet of the CO2 fixation reactor to separate the CO2 fixation products (CaCO3 and MgCO3), and the remaining mixture II is discharged.

[0065] S4: The mixture II is introduced into the catalyst regenerator. The operating temperature of the catalyst regenerator is 50°C, and the residence time of the mixture II in the catalyst regenerator is 60 min. In the catalyst regenerator, the catalyst regeneration reaction can be completed. Solid - liquid separation is carried out at the outlet of the catalyst regenerator to separate the CO2 fixation products (CaCO3 and MgCO3), and the mixture III is discharged. After concentrating the mixture III to an amine catalyst content of 90 wt%, it is introduced into the mixing tank for reuse to achieve the recycling of the amine catalyst.

[0066] Comparative Example 5 The carbon dioxide capture and fixation device for ship exhaust gas in this comparative example is the same as that in Example 1. Using this device, the carbon dioxide in the ship exhaust gas is captured and fixed, and the process is as follows Figure 1 shown, and the specific steps are as follows: S1: Introduce seawater and 2-amino-2-methyl-1-propanol (as an amine catalyst) into a mixing tank for mixing to obtain a seawater / 2-amino-2-methyl-1-propanol mixture, where the content of 2-amino-2-methyl-1-propanol is 30 wt%.

[0067] S2: Feed the seawater / 2-amino-2-methyl-1-propanol mixture and ship exhaust gas into a CO2 capture tower at flow rates of 25 m 3 / h and 5000 m 3 / h respectively. The operating temperature of the CO2 capture tower is 40 °C, the flow rate of the ship exhaust gas in the CO2 capture tower is 1 m / s, and the residence time of the seawater / 2-amino-2-methyl-1-propanol mixture in the CO2 capture tower is 15 min. In the CO2 capture tower, the CO2 absorption reaction can be completed, and at the same time, a partial CO2 fixation precipitation reaction occurs. Decarbonized exhaust gas and mixture I are discharged from the CO2 capture tower.

[0068] S3: Feed mixture I discharged from the CO2 capture tower into a CO2 fixation reactor. The operating temperature of the CO2 fixation reactor is 50 °C, and the residence time of mixture I in the CO2 fixation reactor is 5 min. In the CO2 fixation reactor, the CO2 fixation precipitation reaction can be completed, and at the same time, a partial catalyst regeneration reaction occurs. Solid-liquid separation is carried out at the outlet of the CO2 fixation reactor to separate the CO2 fixation products (CaCO3 and MgCO3), and the remaining mixture II is discharged.

[0069] S4: Feed mixture II into a catalyst regenerator. The operating temperature of the catalyst regenerator is 50 °C, and the residence time of mixture II in the catalyst regenerator is 60 min. In the catalyst regenerator, the catalyst regeneration reaction can be completed. Solid-liquid separation is carried out at the outlet of the catalyst regenerator to separate the CO2 fixation products (CaCO3 and MgCO3), and mixture III is discharged. After concentrating mixture III to an amine catalyst content of 90 wt%, it is fed into the mixing tank for reuse to achieve the recycling of the amine catalyst.

[0070] Comparative Example 6 The carbon dioxide capture and fixation device for ship exhaust gas in this comparative example is the same as that in Example 1. Using this device, the carbon dioxide in the ship exhaust gas is captured and fixed, and the process is as Figure 1 shown. The specific steps are as follows: S1: Introduce seawater and 1-methyl-4-piperidinol (as an amine catalyst) into a mixing tank for mixing to obtain a seawater / 1-methyl-4-piperidinol mixture, where the content of 1-methyl-4-piperidinol is 30 wt%.

[0071] S2: Feed the seawater / 1-methyl-4-piperidinol mixture and the ship exhaust gas into the CO2 capture tower at the flow rates of 25 m 3 / h and 5000 m 3 / h respectively. The operating temperature of the CO2 capture tower is 40 °C. The flow velocity of the ship exhaust gas in the CO2 capture tower is 1 m / s, and the residence time of the seawater / 1-methyl-4-piperidinol mixture in the CO2 capture tower is 15 min. In the CO2 capture tower, the CO2 absorption reaction can be completed, and at the same time, part of the CO2 fixation precipitation reaction occurs. Discharge the decarbonized tail gas and the mixed liquid I from the CO2 capture tower.

[0072] S3: Feed the mixed liquid I discharged from the CO2 capture tower into the CO2 fixation reactor. The operating temperature of the CO2 fixation reactor is 50 °C, and the residence time of the mixed liquid I in the CO2 fixation reactor is 5 min. In the CO2 fixation reactor, the CO2 fixation precipitation reaction can be completed, and at the same time, part of the catalyst regeneration reaction occurs. Perform solid-liquid separation at the outlet of the CO2 fixation reactor to separate the CO2 fixation products (CaCO3 and MgCO3), and discharge the remaining mixed liquid II.

[0073] S4: Feed the mixed liquid II into the catalyst regenerator. The operating temperature of the catalyst regenerator is 50 °C, and the residence time of the mixed liquid II in the catalyst regenerator is 60 min. In the catalyst regenerator, the catalyst regeneration reaction can be completed. Perform solid-liquid separation at the outlet of the catalyst regenerator to separate the CO2 fixation products (CaCO3 and MgCO3), and discharge the mixed liquid III. After concentrating the mixed liquid III to an amine catalyst content of 90 wt%, feed it into the mixing tank for reuse to realize the recycling of the amine catalyst.

[0074] Test Example 1: Performance comparison of different devices and methods In Example 1, Comparative Example 1 and Comparative Example 2, the test ship exhaust gases are the same, and the CO2 concentration in them is 4.5 mol%. The energy consumption, CO2 capture capacity, and the loss of absorbent or catalyst of each device and method are shown in Table 1, where: (1) The "CO2 capture rate" is the percentage of the amount of CO2 captured by the CO2 capture tower to the amount of CO2 in the inlet ship exhaust gas. The calculation formula is as follows: CO2 capture rate = (flue gas inlet flow rate × inlet CO2 concentration - decarbonized flue gas flow rate × outlet CO2 concentration) / (flue gas inlet flow rate × inlet CO2 concentration).

[0075] (2)The energy consumption for the absorbent regeneration in Example 1 is "0 - 0.5 GJ / ton CO2 (heating steam)", which means that heat preservation measures can be adopted, and the heat released by the CO2 absorption reaction is used to supply heat for the catalyst regeneration reaction. In this case, the energy consumption for the absorbent regeneration is 0, and no additional heat supply is required. Or heat preservation measures can be not adopted, and heating steam is used to supply heat for the catalyst regenerator. In this case, the energy consumption for the absorbent regeneration is 0.5 GJ / ton CO2 (heating steam).

[0076] (3)The absorbent loss in Comparative Example 2 is 1 kg / ton CO2 because: the theoretical reaction is that sodium hydroxide (absorbent) reacts with CO2 to form sodium carbonate, and the actual product is a mixture of sodium hydroxide and sodium carbonate, that is, the product contains the absorbent, thus resulting in "absorbent loss".

[0077] Table 1 Performance comparison of different devices and methods

[0078] According to Table 1, it can be seen that: Compared with Comparative Example 1 and Comparative Example 2, in Example 1, the device and method of the present invention can effectively reduce the operation energy consumption of the whole device, and only an additional solid-phase product storage tank needs to be set, which has a smaller floor area compared with the CO2 compression, liquefaction storage tank and liquid-phase product storage tank. In addition, when the devices and methods of Comparative Example 1 and the present invention are adopted, the recycling regeneration of the absorbent or catalyst can be realized. During this process, the catalyst loss of the present invention is significantly lower than the absorbent loss in Comparative Example 1.

[0079] Test Example 2: Performance comparison of different amine catalysts In Examples 1 - 4 and Comparative Examples 3 - 6, the ship exhaust gas used in the tests is the same, and the CO2 concentration therein is 4.5 mol%. The CO2 capture capacity and the amine catalyst loss of each device and method are shown in Table 2, where the meaning and calculation formula of "CO2 capture rate" are the same as those in Table 1.

[0080] Table 2 Performance comparison of different amine catalysts

[0081] According to Table 2, it can be seen that: (1) Compared with Example 1 and Example 2, the loss of amine catalysts in Comparative Example 3 and Comparative Example 4 is relatively high, and the CO2 capture rate in Comparative Example 4 is relatively low. This indicates that a synergistic effect can be generated between diethylenetriamine and 2,2,6,6-tetramethylpiperidine, which can improve the stability of the amine catalyst while ensuring the CO2 capture ability and reduce its loss during long-term operation. The reason for this analysis is as follows: Among the above two components, diethylenetriamine can endow the amine catalyst with good CO2 capture ability, but its degradation loss is relatively high when used alone. Through the conjugation effect and steric effect between diethylenetriamine and 2,2,6,6-tetramethylpiperidine, the stability of both can be improved.

[0082] (2) Compared with Example 3 and Example 4, the CO2 capture rate in Comparative Example 5 and Comparative Example 6 is relatively low, and the loss of amine catalysts is relatively high. This indicates that a synergistic effect can be generated between 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol, which can improve the stability of the amine catalyst while ensuring the CO2 capture ability and reduce its loss during long-term operation. The reason for this analysis is as follows: 2-amino-2-methyl-1-propanol has good CO2 capture ability, but its volatilization loss is relatively high when used alone. When 2-amino-2-methyl-1-propanol is compounded with 1-methyl-4-piperidinol, the intermolecular hydrogen bond formed between the two can be utilized to reduce the volatilization loss of 2-amino-2-methyl-1-propanol. At the same time, 1-methyl-4-piperidinol can provide hydrogen protons for the reaction between 2-amino-2-methyl-1-propanol and CO2, thereby improving the CO2 capture efficiency.

[0083] Unless otherwise defined, all technical terms and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the art to which the present disclosure belongs. The raw materials and equipment used in the present invention are conventional raw materials and equipment in the art and can be obtained from conventional commercial channels unless otherwise specified; the methods used in the present invention are conventional methods in the art unless otherwise specified.

[0084] The above description is only a preferred embodiment of the present invention and does not impose any limitation on the present invention. Any simple modification, change, and equivalent transformation made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for capturing and fixing carbon dioxide in ship exhaust gas, characterized in that, It includes the following steps: S1: Introduce seawater, amine catalyst and ship exhaust gas into the CO2 capture tower to complete the CO2 absorption reaction, and discharge the decarbonized exhaust gas and mixture I; The CO2 absorption reaction includes: ， ， ， where CA is the amine catalyst; S2: Introduce mixture I into the CO2 fixation reactor. After completing the CO2 fixation precipitation reaction, perform solid-liquid separation, and discharge the CO2 fixation product and mixture II; The CO2 fixation precipitation reaction includes: ， ； S3: Introduce mixture II into the catalyst regenerator. After completing the catalyst regeneration reaction, perform solid-liquid separation, and discharge the CO2 fixation product and mixture III. After mixture III is concentrated, it is recycled to S1; The catalyst regeneration reaction includes: ， 。 2. The method according to claim 1, wherein In step S1, the amine catalyst is one of the following a) or b): a) Containing diethylenetriamine and 2,2,6,6-tetramethylpiperidine with a mass ratio of 1:0.0033 to 0.2; b) Containing 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol with a mass ratio of 1:0.15 to 1.

6.

3. The method according to claim 1, characterized in that, In step S1, the CO2 capture tower is a packed tower, a plate tower or a hollow fiber membrane contactor.

4. The method according to claim 1 or 2, characterized in that, In step S1, the operating temperature of the CO2 capture tower is 20 to 80 °C.

5. The method according to claim 1, wherein In step S2, the operating temperature of the CO2 fixation reactor is 20 to 50 °C.

6. The method according to claim 1, wherein In step S3, the operating temperature of the catalyst regenerator is 20 to 50 °C.

7. The method according to claim 1 or 2, characterized in that, In step S1, the specific process of introducing seawater, amine catalyst and ship exhaust gas into the CO2 capture tower includes: mixing seawater and amine catalyst with a mass ratio of 1:0.05 to 4, introducing the obtained mixture of seawater and amine catalyst into the CO2 capture tower, and simultaneously introducing ship exhaust gas into the CO2 capture tower.

8. The method according to claim 7, wherein In step S1, the flow rates of the mixture of seawater and amine catalyst and the ship exhaust gas introduced into the CO2 capture tower are 15 - 30 m 3 / h and 4000 - 6000 m 3 / h respectively. The flow rate of the ship exhaust gas in the CO2 capture tower is 1 - 3 m / s, and the residence time of the mixture of seawater and amine catalyst in the CO2 capture tower is 5 - 45 min; in step S2, the residence time of the mixed liquid I in the CO2 fixation reactor is 0 - 20 min; in step S3, the residence time of the mixed liquid II in the catalyst regenerator is 30 - 120 min.

9. The method according to claim 1, characterized in that In step S3, after concentrating mixture III until the amine catalyst content is not less than 85 wt%, it is recycled to S1.

10. An apparatus for capturing and fixing carbon dioxide in ship exhaust gas by using the method according to any one of claims 1 to 9, characterized in that, It includes a mixing tank, a CO2 capture tower, a CO2 fixation reactor and a catalyst regenerator connected in sequence; A seawater inlet and a catalyst inlet are provided in the mixing tank; A ship exhaust gas inlet and a decarbonized exhaust gas outlet are provided in the CO2 capture tower; Solid-liquid separators and CO2 fixation product outlets are provided in the CO2 fixation reactor and the catalyst regenerator; The catalyst regenerator is connected to the mixing tank.

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