Method for regenerating and recycling absorption rich solution of CO2 / SO2 capture by organic amine method

Abstract

This invention discloses a method for regenerating and utilizing the rich absorbent solution for capturing CO2 / SO2 using an organic amine method, comprising the following steps: S1. For the rich absorbent solution system obtained by treating CO2 / SO2 mixed gas with organic amine, CO2 gas is desorbed using a first-stage thermal desorption method, and then an alkaline solution M(OH) is introduced. n SO3 in the rich solution 2‑ Primary mineralization is M(SO3). n / 2 Precipitate forms and a mother liquor is obtained; S2. CO2 is continuously passed into the mother liquor to remove inorganic cation M. n+ Secondary mineralization is M(CO3). n / 2 After precipitation, residual CO2 gas in the mother liquor is desorbed using a two-stage thermal desorption method, thereby regenerating the organic amine solution. This method employs two-stage series mineralization and two-stage series pyrolysis to ensure high-purity regeneration of the organic amine solution, while simultaneously producing sulfite and carbonate products, achieving the resource-based conversion of CO2 and SO2 in the absorbent solution.

Description

Technical Field

[0001] This invention relates to the field of organic amine regeneration technology, and in particular to a method for regenerating and resource-utilizing CO2 / SO2 capture and absorption-rich solutions using organic amines. Background Technology

[0002] Organic amine capture of CO2 is currently the most common method for CO2 separation. However, the composition of flue gas is very complex. Power plants in my country mostly produce coal-fired flue gas, which has a complex composition. Therefore, in addition to CO2, the flue gas after combustion also contains dust and NO. X Components such as SO2 are present. The front-end desulfurization process often cannot completely remove SO2. A small amount of SO2 enters the decarbonization process. SO2 is more acidic and cannot be removed by thermal desorption under alkaline conditions after combining with organic amines.

[0003] Jubao Gao et al. (Effect of SO2 on the amine-based CO2 capture solvent and improvement using ion exchange resins) addressed the regeneration of CO2 / SO2 absorbent solutions by using alkaline anion exchange resins to remove SO2 and thermally stable sulfates from the absorbent solution. In a stable operating system, the content of thermally stable salts, including sulfates, is ≤1 wt%. However, this method has drawbacks such as high cost and difficulty in resource utilization.

[0004] CN108704445A (Li Chun, Liu Weizao, Wang Liming, Liang Bin. A method for reducing the energy consumption of organic amine regeneration coupled with blast furnace slag mineralization) involves mixing blast furnace slag with CO2-loaded organic amine in a certain proportion and adding it to a pyrolysis reactor. Regenerated organic amine is obtained through mineralization and pyrolysis processes. The disadvantage of this method is that it is difficult to completely remove CO2 from the rich liquor and it is not suitable for absorption liquor containing both CO2 and SO2.

[0005] In organic amine method for capturing CO2 / SO2 in absorption-rich solutions, the main forms of CO2 / SO2 are carbamates and HCO3-. - / CO3 2- SO3 2- Traditional thermal desorption methods cannot effectively remove SO3 from solutions. 2- The CaCO3 method for mineralization and desorption cannot effectively remove HCO3 from the solution. - / CO3 2- To date, there have been no reports on the research and application of simultaneous mineralization and pyrolysis of CO2 / SO2 absorption-rich solutions captured by organic amine methods. Summary of the Invention

[0006] In order to achieve the regeneration of CO2 / SO2 capture-rich absorbent solution using the organic amine method, and simultaneously realize the resource utilization of CO2 and SO2, this invention provides a method for the regeneration and resource utilization of CO2 / SO2 capture-rich absorbent solution using the organic amine method.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for regenerating and utilizing CO2 / SO2-rich absorbent solutions using organic amines includes the following steps:

[0009] S1. For the absorbent-rich system obtained by treating CO2 / SO2 mixed gas with organic amines, after desorbing CO2 gas using a first-stage thermal desorption method, an alkaline solution M(OH) is introduced. n SO3 in the rich solution 2- Primary mineralization is M(SO3). n / 2 The precipitate forms and the mother liquor is obtained;

[0010] S2. Continue to pass CO2 into the mother liquor to remove inorganic cation M n+ Secondary mineralization is M(CO3). n / 2 After precipitation, a two-stage thermal desorption method is used to desorb the residual CO2 gas in the mother liquor, thereby regenerating the organic amine solution.

[0011] Preferably, the absorption-rich liquid system is a weakly alkaline solution obtained after organic amines absorb CO2 / SO2 mixed gas to absorption saturation.

[0012] Preferably, the compound M is M(OH). n It is water-soluble, M(CO3) n / 2 And M(SO3) n / 2 It is insoluble in water.

[0013] Preferably, M includes, but is not limited to, Ca and Ba.

[0014] Preferably, M in the alkaline solution n+ With absorption of SO3 in rich solution 2- The molar ratio of substances is (1-10):1.

[0015] Preferably, the conditions for the primary thermal desorption method are 100-140℃ for 1-3 hours, and the conditions for primary mineralization are 20-30℃ for 3-5 hours.

[0016] Preferably, the secondary mineralization conditions are 20-30℃ for 1-3 hours, and the conditions for the secondary thermal desorption method are 100-140℃ for 2-4 hours.

[0017] Design concept and principle of the present invention

[0018] (1) Primary thermal desorption

[0019] The first-order thermal desorption equation used is:

[0020]

[0021]

[0022] pK of H2SO3 in the absorption solution a1 Value, pK a2 The values ​​were 1.9 and 7.2 respectively; while the pK of H2CO3 was... a1 Value, pK a2 The values ​​were 6.38 and 10.25, respectively. H2SO3 has a lower pK... a Value leads to SO3 2- It is difficult for it to combine with protons in alkaline solution to form unstable HSO3. - It may have an H2SO3 structure, therefore SO3 is the dominant component in the rich solution. 2- SO2 in its current form is difficult to remove effectively by thermal desorption, while HCO3- in the rich solution is the more readily removed form. - / CO3 2- CO2 in its present form is easily removed by thermal desorption.

[0023] (2) Primary mineralization

[0024] The first-order mineralization equation used

[0025]

[0026] M(SO3) obtained from primary mineralization n / 2 The crude product undergoes multiple washing processes to remove M(OH). n After reacting with the organic amine solution adhering to the surface, relatively pure M(SO3) can be obtained. n / 2 product.

[0027] (3) Secondary mineralization

[0028] The second-order mineralization equation used

[0029]

[0030] M(CO3) obtained from secondary mineralization n / 2 The crude product undergoes multiple washing processes to remove M(OH). n After reacting with the organic amine solution adhering to the surface, relatively pure M(CO3) can be obtained. n / 2 product.

[0031] (4) Secondary pyrolysis

[0032] The second-order thermal desorption equation used

[0033]

[0034]

[0035] Heating the mother liquor to 100-140℃ and then refluxing at that temperature for thermal desorption can desorb all CO2, thus regenerating the organic amine solution.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] 1. CO2 is removed from the rich solution through a series of primary and secondary thermal desorption processes, achieving efficient regeneration of organic amines;

[0038] 2. CO2 and SO2 in the rich solution are removed by a series of primary and secondary mineralization processes, achieving efficient purification of organic amines;

[0039] 3. The mineralized products can be further separated and utilized as resources.

[0040] 4. It achieves a near 100% organic amine regeneration rate, which can fully remove CO2 / SO2 from the rich solution, and the CO2 and SO2 in the rich solution can be recycled. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a process flow diagram of the present invention;

[0043] Figure 2 XRD diffraction patterns of the CaSO3 sample prepared in Example 1 and the CaSO3 standard card;

[0044] Figure 3 The figures show the XRD diffraction patterns of the CaCO3 sample and the monoclinic CaCO3 standard card in Example 1; where A represents the CaCO3 product; B represents the orthorhombic CaCO3 standard card; and C represents the monoclinic CaCO3 standard card. As can be seen from the figures, the CaCO3 product prepared by the invention has two crystal forms: monoclinic and orthorhombic. Detailed Implementation

[0045] Unless otherwise stated, all raw materials and reagents used in this invention are commercially available products, or can be directly customized from a chemical reagent customization factory, or prepared in-house.

[0046] To date, there have been no reports on the research and application of simultaneous mineralization and pyrolysis of CO2 / SO2 absorption solutions captured by organic amine methods.

[0047] Compared with the traditional absorption-rich solution regeneration technology for CO2 absorption by organic amines, this method adopts a two-stage thermal desorption and two-stage mineralization process to achieve efficient regeneration of organic amines, efficient removal of CO2 and SO2 from the rich solution, and resource utilization.

[0048] Example 1

[0049] A rich solution was obtained by absorbing a CO2 / SO2 mixture with a 30wt% N-aminoethylpiperazine aqueous solution, wherein the CO2 content was 0.74 mol / mol and the SO2 content was 0.1 mol / mol.

[0050] The alkaline substance is Ca(OH)2.

[0051] The specific operating steps are as follows:

[0052] S1. Take 30g of the rich solution and place it in a 50mL three-necked flask. Under nitrogen atmosphere, desorb at 120℃ for 3h until CO2 desorption is complete, and obtain mother liquor 1; follow M... n+ SO3 2- The molar ratio is 1.2:1. Ca(OH)2 is added to mother liquor 1, and after primary mineralization at room temperature (20-30℃) for 4 hours, mother liquor 2 and filter cake 1 are obtained by filtration and separation. After multiple washings, CaSO3 is obtained from filter cake 1.

[0053] S2. CO2 is introduced into mother liquor 2, and secondary mineralization is carried out at room temperature (20-30℃) for 2 hours. After filtration, mother liquor 3 and filter cake 2 are obtained. After multiple washings, CaCO3 is obtained from filter cake 2. Mother liquor 3 is desorbed at 120℃ under nitrogen atmosphere for 3 hours until CO2 is completely desorbed, and a high-purity N-aminoethylpiperazine solution is regenerated.

[0054] Example 2

[0055] A rich solution was obtained by absorbing a CO2 / SO2 mixture with a 30wt% N-hydroxyethylpiperazine aqueous solution, wherein the CO2 content was 0.26 mol / mol and the SO2 content was 0.1 mol / mol.

[0056] The alkaline substance is Ca(OH)2.

[0057] The specific operating steps are as follows:

[0058] S1. Take 30g of the rich solution and place it in a 50mL three-necked flask. Under nitrogen atmosphere, desorb at 120℃ for 3h until CO2 desorption is complete, and obtain mother liquor 1; follow M... n+ SO3 2-The molar ratio is 1.2:1. Ca(OH)2 is added to mother liquor 1, and after primary mineralization at room temperature (20-30℃) for 4 hours, mother liquor 2 and filter cake 1 are obtained by filtration and separation. After multiple washings, CaSO3 is obtained from filter cake 1.

[0059] S2. CO2 is introduced into mother liquor 2, and secondary mineralization is carried out at room temperature (20-30℃) for 2 hours. After filtration, mother liquor 3 and filter cake 2 are obtained. After multiple washings, CaCO3 is obtained from filter cake 2. Mother liquor 3 is desorbed at 120℃ under nitrogen atmosphere for 3 hours until CO2 is completely desorbed, and a high-purity N-aminoethylpiperazine solution is regenerated.

[0060] Example 3

[0061] A rich solution was obtained by absorbing a CO2 / SO2 mixture with a 30wt% N-aminoethylpiperazine aqueous solution, wherein the CO2 content was 0.69 mol / mol and the SO2 content was 0.12 mol / mol.

[0062] The alkaline substance is Ba(OH)2·8H2O.

[0063] The specific operating steps are as follows:

[0064] S1. Take 30g of the rich solution and place it in a 50mL three-necked flask. Under nitrogen atmosphere, desorb at 120℃ for 3h until CO2 desorption is complete, and obtain mother liquor 1; follow M... n+ SO3 2- The molar ratio is 1.2:1. Ba(OH)2·8H2O is added to mother liquor 1. After primary mineralization at room temperature (20-30℃) for 4 hours, mother liquor 2 and filter cake 1 are obtained by filtration. After multiple washings, BaSO3 is obtained.

[0065] S2. CO2 is introduced into mother liquor 2, and secondary mineralization is carried out at room temperature (20-30℃) for 2 hours. After filtration, mother liquor 3 and filter cake 2 are obtained. After multiple washings, BaCO3 is obtained from filter cake 2. Mother liquor 3 is desorbed at 120℃ under nitrogen atmosphere for 3 hours until CO2 is completely desorbed, and a high-purity N-aminoethylpiperazine solution is regenerated.

[0066] Example 4

[0067] A rich solution was obtained by absorbing a CO2 / SO2 mixture with a 30wt% N-aminoethylpiperazine aqueous solution, wherein the CO2 content was 0.74 mol / mol and the SO2 content was 0.10 mol / mol.

[0068] The alkaline substance is a saturated solution of Ca(OH)2.

[0069] The specific operating steps are as follows:

[0070] S1. Take 30g of the rich solution and place it in a 50mL three-necked flask. Under nitrogen atmosphere, desorb at 120℃ for 3h until CO2 desorption is complete, and obtain mother liquor 1; follow M... n+ SO3 2- With a molar ratio of 1.2:1, a saturated Ca(OH)2 solution was added to mother liquor 1. After primary mineralization at room temperature (20-30℃) for 4 hours, mother liquor 2 and filter cake 1 were obtained by filtration. After multiple washings, CaSO3 was obtained from filter cake 1.

[0071] S2. CO2 is introduced into mother liquor 2, and secondary mineralization is carried out at room temperature (20-30℃) for 2 hours. After filtration, mother liquor 3 and filter cake 2 are obtained. After multiple washings, CaCO3 is obtained from filter cake 2. Mother liquor 3 is desorbed at 120℃ under nitrogen atmosphere for 3 hours until CO2 is completely desorbed, and a high-purity N-aminoethylpiperazine solution is regenerated.

[0072] Example 5

[0073] A rich solution was obtained by absorbing a CO2 / SO2 mixture from a 30wt% N-hydroxyethylpiperazine aqueous solution, wherein the CO2 content was 0.28 mol / mol and the SO2 content was 0.08 mol / mol.

[0074] The alkaline substance is a saturated solution of Ca(OH)2.

[0075] The specific operating steps are as follows:

[0076] S1. Take 30g of the rich solution and place it in a 50mL three-necked flask. Under nitrogen atmosphere, desorb at 120℃ for 3h until CO2 desorption is complete, and obtain mother liquor 1; follow M... n+ SO3 2- With a molar ratio of 1.2:1, a saturated Ca(OH)2 solution was added to mother liquor 1. After primary mineralization at room temperature (20-30℃) for 4 hours, mother liquor 2 and filter cake 1 were obtained by filtration. After multiple washings, CaSO3 was obtained from filter cake 1.

[0077] S2. CO2 is introduced into mother liquor 2, and secondary mineralization is carried out at room temperature (20-30℃) for 2 hours. After filtration, mother liquor 3 and filter cake 2 are obtained. After multiple washings, CaCO3 is obtained from filter cake 2. Mother liquor 3 is desorbed at 120℃ under nitrogen atmosphere for 3 hours until CO2 is completely desorbed, and a high-purity N-aminoethylpiperazine solution is regenerated.

[0078] Table 1 shows the absorption capacity of organic amines for CO2 / SO2 capture in different rich absorbent solutions described in Examples 1-5, and the absorption capacity of organic amines for CO2 absorption after regeneration compared with the initial absorption capacity of organic amines.

[0079] Table 1. CO2 absorption capacity of organic amine solutions before and after regeneration

[0080]

[0081] As can be seen from the examples and comparative examples, the organic amine solution regenerated using the technology of the present invention has the same CO2 absorption capacity as the bulk organic amine solution, indicating that the technology of the present invention fully realizes the regeneration of organic amine and can prepare relatively pure CaSO3 and CaCO3.

[0082] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for capturing CO2 / SO2 using organic amines, regenerating and utilizing the rich solution, characterized in that... Includes the following steps: S1. For the absorbent-rich system obtained by treating CO2 / SO2 mixed gas with organic amines, after desorbing CO2 gas using a first-stage thermal desorption method, an alkaline solution M(OH) is introduced. n SO3 in the rich solution 2- Primary mineralization is M(SO3). n / 2 A precipitate forms, and a mother liquor is obtained; M is selected from Ca or Ba; S2. Continue to pass CO2 into the mother liquor to remove inorganic cation M n+ Secondary mineralization is M(CO3). n / 2 After precipitation, a two-stage thermal desorption method is used to desorb the residual CO2 gas in the mother liquor, thereby regenerating the organic amine solution.

2. The method for regenerating and resource-utilizing CO2 / SO2 absorption solution using organic amines according to claim 1, characterized in that, The rich absorption solution system is a weakly alkaline solution obtained after organic amines absorb CO2 / SO2 mixed gas to the point of absorption saturation.

3. The method for regenerating and resource-utilizing CO2 / SO2 absorption solution using organic amines according to claim 1, characterized in that, The compound M(OH) of M. n It is water-soluble, M(CO3) n / 2 And M(SO3) n / 2 It is insoluble in water.

4. The method for capturing, regenerating, and utilizing CO2 / SO2-rich absorbent solution using the organic amine method according to claim 1, characterized in that, M in the alkaline solution n+ With absorption of SO3 in rich solution 2- The molar ratio of substances is (1-10):

1.

5. The method for regenerating and resource-utilizing CO2 / SO2 absorption solution using organic amines according to claim 1, characterized in that, The conditions for the first-stage thermal desorption method are 100-140℃ for 1-3 hours, and the conditions for the first-stage mineralization method are 20-30℃ for 3-5 hours.

6. The method for capturing CO2 / SO2 using organic amines, regenerating and utilizing the rich solution, as described in claim 1, is characterized in that... The secondary mineralization conditions are 20-30℃ for 1-3 hours, and the conditions for the secondary thermal desorption method are 100-140℃ for 2-4 hours.

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