Amine liquid purification method and system for carbon dioxide capture system

Abstract

The invention relates to the technical field of carbon capture, in particular to an amine liquid purification method and system for a carbon dioxide capture system. The amine liquid purification method for the carbon dioxide capture system comprises the following steps: A) conveying rich liquid after carbon dioxide capture to a regeneration tower for desorption; b) conveying a part of the desorbed barren solution to a residual CO2 removal device for CO2 separation; c) conveying the barren liquor treated in the step B) to a barren liquor cooler for cooling; d) conveying the cooled barren liquor to a precision filter for filtering; and E) conveying the filtered barren liquor to a solvent purification device to separate the thermally stable salt, and reusing the separated barren liquor in a carbon dioxide capture system. According to the amine liquid purification method and system for the carbon dioxide capture system, the amine liquid can be effectively purified.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon capture, and in particular to an amine liquid purification method and system for a carbon dioxide capture system. Background Art

[0002] Carbon capture, utilization and storage (CCUS) is an emerging technology that is expected to achieve large-scale carbon sinks from fossil energy. It is an important means to reduce CO2 emissions, ensure energy security and achieve sustainable development in the future. Among them, the solvent absorption method based on organic amine liquid is one of the most effective methods for carbon dioxide gas. The amine liquid after absorbing carbon dioxide enters the regeneration tower as a rich liquid. At the operating temperature of 110-130°C in the regeneration tower, it inevitably undergoes degradation reactions with the components in the flue gas to generate a series of heat stable salts (HSS). The continuously accumulated HSS causes the loss of amine liquid, affects the efficiency of the absorbent and causes corrosion to the carbon capture device. Therefore, amine solvent purification is of great significance to reduce absorbent loss and improve capture performance.

[0003] In other industries, the process of filtration + ion exchange for solvent purification is relatively common. If it is directly used in the carbon dioxide capture system, the excessively high CO2 content and temperature in the lean liquid will reduce the life of the resin or membrane, increase the loss of amine, and reduce the efficiency of the amine liquid purification system. The technical solution of the present invention solves the above problems very well. Summary of the invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide an amine liquid purification method and system for a carbon dioxide capture system, which can effectively purify the amine liquid.

[0005] The present invention provides an amine liquid purification method for a carbon dioxide capture system, comprising the following steps:

[0006] A) transporting the rich liquid after carbon dioxide capture to a regeneration tower for desorption;

[0007] B) transporting the desorbed lean liquid to a residual CO2 removal device for CO2 separation;

[0008] C) transporting the lean liquid treated in step B) to a lean liquid cooler for cooling;

[0009] D) conveying the cooled lean liquid to a precision filter for filtration;

[0010] E) transporting the filtered lean liquid to a solvent purification device to separate heat-stable salts, and the separated lean liquid is reused in the carbon dioxide capture system.

[0011] Preferably, in step A), the mass content of the heat-stable salt in the lean solution after desorption is 1.0% to 1.5%, and the molar ratio of the amine to CO2 is 1:0.15 to 0.25.

[0012] Preferably, in step B), the partial lean liquid after desorption accounts for 1% to 10% of the mass of the total lean liquid after desorption.

[0013] Preferably, in step B), after separation of CO2, the molar ratio of amine to CO2 in the obtained lean liquid is 1:0.03-0.07.

[0014] Preferably, in step C), the temperature of the cooled lean liquid is 20-30°C.

[0015] Preferably, in step D), the filtration accuracy is 5 to 10 μm.

[0016] Preferably, in step E), the solvent purification device is an electrodialysis device, and the membrane parameters include: thickness 150 μm, resistance 1.9 Ω·cm 2 , bursting strength>0.5Mpa, operating temperature 25~40℃, operating pH 2~10.

[0017] Preferably, in step E), the solvent purification device may also be an ion resin exchange device, and the parameters of the ion resin exchange device include:

[0018] The resin parameter is 1.35mmol·mL -1 , operating temperature 25-40℃, operating pH 2-10.

[0019] The present invention also provides an amine liquid purification system for a carbon dioxide capture system, comprising:

[0020] Regeneration tower;

[0021] A residual CO2 removal device connected to the lean liquid outlet of the regeneration tower;

[0022] a lean liquid cooler connected to the lean liquid outlet of the excess CO2 removal device;

[0023] A precision filter connected to the lean liquid outlet of the lean liquid cooler;

[0024] A solvent purification device connected to the lean liquid outlet of the precision filter.

[0025] Preferably, the lean liquid outlet of the solvent purification device is connected to a carbon dioxide capture system.

[0026] The present invention provides an amine liquid purification method for a carbon dioxide capture system, comprising the following steps: A) transporting the rich liquid after carbon dioxide capture to a regeneration tower for desorption; B) transporting part of the lean liquid after desorption to a residual CO2 removal device for CO2 separation; C) transporting the lean liquid treated in step B) to a lean liquid cooler for cooling; D) transporting the cooled lean liquid to a precision filter for filtration; E) transporting the filtered lean liquid to a solvent purification device to separate heat-stable salts, and the separated lean liquid is reused in the carbon dioxide capture system. The amine liquid purification method and system for a carbon dioxide capture system provided by the present invention can effectively purify the amine liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A diagram of an amine liquid purification system for a carbon dioxide capture system provided in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The present invention provides an amine liquid purification method for a carbon dioxide capture system, comprising the following steps:

[0030] A) transporting the rich liquid after carbon dioxide capture to a regeneration tower for desorption;

[0031] B) transporting the desorbed lean liquid to a residual CO2 removal device for CO2 separation;

[0032] C) transporting the lean liquid treated in step B) to a lean liquid cooler for cooling;

[0033] D) conveying the cooled lean liquid to a precision filter for filtration;

[0034] E) transporting the filtered lean liquid to a solvent purification device to separate the heat-stable salt, and the separated lean liquid is reused in the carbon dioxide capture system.

[0035] In step A):

[0036] The rich liquid after carbon dioxide capture is transported to the regeneration tower for desorption.

[0037] The rich liquid after carbon dioxide capture is an organic amine aqueous solution that has absorbed carbon dioxide, wherein the molar ratio of carbon dioxide to amine group is 0.8-1.0:1.0, such as 1.0:1.0. The organic amine aqueous solution is a MEA solution or a MEDA solution; the mass concentration of the organic amine aqueous solution is 20%-30%, such as 25%.

[0038] The desorption temperature is 105-115°C, such as 110°C.

[0039] The desorbed carbon dioxide is discharged from the top of the regeneration tower.

[0040] The desorbed lean solution includes amine, heat-stable salt and a small amount of CO2. In the desorbed lean solution, the mass content of the heat-stable salt is 1.0% to 1.5%, such as 1%; the molar ratio of the amine to CO2 is 1:0.15 to 0.25, such as 1:0.2. The heat-stable salt includes at least one of carbamate, aminoacetate and aminooxalate.

[0041] In step B):

[0042] The desorbed lean liquid is transported to a residual CO2 removal device for CO2 separation.

[0043] The part of lean liquid after desorption accounts for 1% to 10% of the mass of the whole lean liquid after desorption, for example, 1%.

[0044] After separation of CO2, the molar ratio of amine to CO2 in the obtained lean liquid is 1:0.03-0.07, for example, 1:0.05.

[0045] In step C):

[0046] The lean liquid treated in step B) is transported to a lean liquid cooler for cooling.

[0047] The temperature of the cooled lean liquid is 20-30°C, such as 25°C.

[0048] In step D):

[0049] The cooled lean liquid is transported to a precision filter for filtration.

[0050] The filtration accuracy is 5-10 μm, for example, 5 μm. The filtration is used to remove suspended matter in the barren liquid.

[0051] In step E):

[0052] The filtered lean liquid is transported to a solvent purification device to separate heat-stable salts, and the separated lean liquid is reused in the carbon dioxide capture system.

[0053] In some embodiments of the present invention, the solvent purification device is an electrodialysis device, and the membrane parameters include: thickness 150 μm; resistance 1.9 Ω·cm 2 ; burst strength> 0.5Mpa; operating temperature is 25-40°C, such as 25°C; operating pH value is 2-10, such as 9. In the barren solution treated by the electrodialysis device, the mass content of the heat-stable salt is reduced to 0.1%-0.5%, such as 0.5%.

[0054] In some embodiments of the present invention, the solvent purification device may also be an ion resin exchange device, and the parameters of the ion resin exchange device include:

[0055] The resin parameter is 1.35mmol·mL -1 , the operating temperature is 25 to 40°C, and the operating pH value is 2 to 10. In the lean liquid treated by the ion resin exchange device, the mass content of the heat-stable salt is reduced to 0.1% to 0.5%, such as 0.4%.

[0056] The present invention provides an amine liquid purification system for a carbon dioxide capture system for implementing the above method, comprising:

[0057] Regeneration tower;

[0058] A residual CO2 removal device connected to the lean liquid outlet of the regeneration tower;

[0059] a lean liquid cooler connected to the lean liquid outlet of the excess CO2 removal device;

[0060] A precision filter connected to the lean liquid outlet of the lean liquid cooler;

[0061] A solvent purification device connected to the lean liquid outlet of the precision filter.

[0062] Figure 1 A diagram of an amine liquid purification system for a carbon dioxide capture system provided for an embodiment of the present invention, wherein 1 is a first pipeline, 2 is a regeneration tower, 3 is a second pipeline, 4 is a third pipeline, 5 is a residual CO2 removal device, 6 is a fourth pipeline, 7 is a fifth pipeline, 8 is a lean liquid cooler, 9 is a sixth pipeline, 10 is a precision filter, 11 is a solvent purification device, 12 is a seventh pipeline, and 13 is an eighth pipeline.

[0063] The amine liquid purification system for a carbon dioxide capture system provided by the present invention comprises a regeneration tower 2. The regeneration tower is generally commercially available. The rich liquid after carbon dioxide capture is transported to the regeneration tower via a first pipeline 1 for desorption, and most of the carbon dioxide can be desorbed and discharged from the gas outlet of the regeneration tower via a second pipeline 3.

[0064] The amine liquid purification system for a carbon dioxide capture system provided by the present invention further comprises a residual CO2 removal device 5 connected to the lean liquid outlet of the regeneration tower. The residual CO2 removal device is used to separate the residual CO2 in the lean liquid. The carbon dioxide in the residual CO2 removal device is discharged from the gas outlet of the residual CO2 removal device via a fourth pipeline 6.

[0065] The excess CO2 removal device is a flash tank.

[0066] The excess CO2 removal device is connected to the lean liquid outlet of the regeneration tower through a third pipeline 4. The third pipeline includes a branch pipe, which is provided with an inlet, a first outlet and a second outlet. The inlet of the third branch pipe is connected to the lean liquid outlet of the regeneration tower, the first outlet of the third branch pipe is connected to the lean liquid inlet of the excess CO2 removal device, and the second outlet of the third branch pipe is connected to the carbon dioxide capture system.

[0067] The amine liquid purification system for a carbon dioxide capture system provided by the present invention further comprises a lean liquid cooler 8 connected to the lean liquid outlet of the residual CO2 removal device. The lean liquid discharged from the residual CO2 removal device is transported to the lean liquid cooler for cooling. The pipeline connecting the residual CO2 removal device and the lean liquid cooler is a fifth pipeline 7.

[0068] The lean liquid cooler is generally commercially available.

[0069] The amine liquid purification system for the carbon dioxide capture system provided by the present invention further comprises a precision filter 10 connected to the lean liquid outlet of the lean liquid cooler. The precision filter is used to filter and cool the lean liquid. The pipeline connecting the lean liquid cooler and the precision filter is the sixth pipeline 9.

[0070] The precision filter is generally commercially available.

[0071] The amine liquid purification system for the carbon dioxide capture system provided by the present invention further comprises a solvent purification device 11 connected to the lean liquid outlet of the precision filter. The solvent purification device is used to separate heat-stable salt from the lean liquid.

[0072] In some embodiments of the present invention, the solvent purification device is an electrodialysis device, and the membrane parameters include: thickness 150 μm; resistance 1.9 Ω·cm 2 ; burst strength> 0.5Mpa; operating temperature is 25-40°C, such as 25°C; operating pH value is 2-10, such as 9. In the barren solution treated by the electrodialysis device, the mass content of the heat-stable salt is reduced to 0.1%-0.5%, such as 0.5%.

[0073] The electrodialysis device is generally commercially available.

[0074] In some embodiments of the present invention, the solvent purification device may also be an ion resin exchange device, and the parameters of the ion resin exchange device include:

[0075] The resin parameter is 1.35mmol·mL -1 , the operating temperature is 25 to 40°C, and the operating pH value is 2 to 10. In the lean liquid treated by the ion resin exchange device, the mass content of the heat-stable salt is reduced to 0.1% to 0.5%, such as 0.4%.

[0076] The heat-stable salt in the solvent purification device is discharged through the heat-stable salt outlet of the solvent purification device through the seventh pipeline 12.

[0077] The lean liquid outlet of the solvent purification device is connected to the carbon dioxide capture system. Specifically, the lean liquid outlet of the solvent purification device is connected to the carbon dioxide capture system through an eighth pipeline 13.

[0078] The present invention has no special restrictions on the source of the raw materials used above, and they can be generally commercially available. The material of each of the pipes is SS304.

[0079] In order to further illustrate the present invention, an amine liquid purification method and system for a carbon dioxide capture system provided by the present invention are described in detail below in conjunction with embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0080] Example 1

[0081] Use Figure 1 The amine liquid purification system shown is used for amine liquid purification:

[0082] 1) The rich liquid after carbon dioxide capture (organic amine aqueous solution that has absorbed carbon dioxide, wherein the molar ratio of carbon dioxide to amine group is 1.0:1.0; the organic amine aqueous solution is a MEA solution with a mass concentration of 25%) is transported to the regeneration tower 2 through the first pipeline 1 for desorption at 110° C. The desorbed carbon dioxide is discharged from the gas outlet of the regeneration tower through the second pipeline 3;

[0083] In the lean liquid after desorption, the mass content of the heat-stable salt is 1%, and the molar ratio of the amine to CO2 is 1:0.2;

[0084] 2) The part of the lean liquid after desorption (the part of the lean liquid after desorption accounts for 1% of the mass of the total lean liquid after desorption) is transported to the residual CO2 removal device 5 (flash tank) via the third pipeline 4 for CO2 separation;

[0085] The third pipeline includes a branch pipe, and is provided with an inlet, a first outlet, and a second outlet. The inlet of the third branch pipe is connected to the lean liquid outlet of the regeneration tower, the first outlet of the third branch pipe is connected to the lean liquid inlet of the excess CO2 removal device, and the second outlet of the third branch pipe is connected to the carbon dioxide capture system;

[0086] After CO2 separation, the molar ratio of amine to CO2 in the obtained lean liquid is 1:0.05;

[0087] The carbon dioxide in the residual CO2 removal device is discharged from the gas outlet of the residual CO2 removal device via the fourth pipeline 6;

[0088] 3) The lean liquid after the treatment in step 2) is transported to the lean liquid cooler 8 via the fifth pipeline 7 to be cooled to 25° C.;

[0089] 4) The cooled lean liquid is transported to the precision filter 10 via the sixth pipeline 9 for filtration;

[0090] The filtration accuracy is 5 μm;

[0091] 5) The filtered lean liquid is transported to a solvent purification device 11 to separate the heat-stable salt, and the separated lean liquid is reused in the carbon dioxide capture system;

[0092] The solvent purification device is an electrodialysis device, and the membrane parameters include: thickness 150 μm, resistance 1.9 Ω·cm 2 , burst strength>0.5Mpa, operating temperature is 25℃, operating pH value is 9; in the barren liquid after treatment by the electrodialysis device, the mass content of heat-stable salt is reduced to 0.5%.

[0093] The heat-stable salt in the solvent purification device is discharged through the heat-stable salt outlet of the solvent purification device through the seventh pipeline 12;

[0094] The lean liquid outlet of the solvent purification device is connected to the carbon dioxide capture system through the eighth pipeline 13. The lean liquid discharged from the lean liquid outlet of the solvent purification device has a mass content of 0.5% of heat-stable salt.

[0095] Example 2

[0096] Use Figure 1 The amine liquid purification system shown is used for amine liquid purification:

[0097] 1) The rich liquid after carbon dioxide capture (organic amine aqueous solution that has absorbed carbon dioxide; the organic amine aqueous solution is a MEA solution with a mass concentration of 25%) is transported to the regeneration tower 2 through the first pipeline 1 for desorption at 110° C. The desorbed carbon dioxide is discharged from the gas outlet of the regeneration tower through the second pipeline 3;

[0098] In the lean liquid after desorption, the mass content of the heat-stable salt is 1%, and the molar ratio of the amine to CO2 is 1:0.2;

[0099] 2) The part of the lean liquid after desorption (the part of the lean liquid after desorption accounts for 1% of the mass of the total lean liquid after desorption) is transported to the residual CO2 removal device 5 (flash tank) via the third pipeline 4 for CO2 separation;

[0100] The third pipeline includes a branch pipe, and is provided with an inlet, a first outlet, and a second outlet. The inlet of the third branch pipe is connected to the lean liquid outlet of the regeneration tower, the first outlet of the third branch pipe is connected to the lean liquid inlet of the excess CO2 removal device, and the second outlet of the third branch pipe is connected to the carbon dioxide capture system;

[0101] After CO2 separation, the molar ratio of amine to CO2 in the obtained lean liquid is 1:0.05;

[0102] The carbon dioxide in the residual CO2 removal device is discharged from the gas outlet of the residual CO2 removal device via the fourth pipeline 6;

[0103] 3) The lean liquid after the treatment in step 2) is transported to the lean liquid cooler 8 via the fifth pipeline 7 to be cooled to 25° C.;

[0104] 4) The cooled lean liquid is transported to the precision filter 10 via the sixth pipeline 9 for filtration;

[0105] The filtration accuracy is 5 μm;

[0106] 5) The filtered lean liquid is transported to a solvent purification device 11 to separate the heat-stable salt, and the separated lean liquid is reused in the carbon dioxide capture system;

[0107] The solvent purification device is an ion resin exchange device, and the parameters of the ion resin exchange device include: resin parameters are 1.35mmol·mL -1 , operating temperature 25 ~ 40 ℃, operating pH value 2 ~ 10; the mass content of heat-stable salt in the lean liquid after treatment by the ion resin exchange device is reduced to 0.4%.

[0108] The heat-stable salt in the solvent purification device is discharged through the heat-stable salt outlet of the solvent purification device through the seventh pipeline 12;

[0109] The lean liquid outlet of the solvent purification device is connected to the carbon dioxide capture system through the eighth pipeline 13. The lean liquid discharged from the lean liquid outlet of the solvent purification device has a mass content of 0.4% of heat-stable salt.

[0110] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for purifying an amine solution for a carbon dioxide capture system, comprising the following steps: A) transporting the rich liquid after carbon dioxide capture to a regeneration tower for desorption; B) transporting the desorbed lean liquid to a residual CO2 removal device for CO2 separation; C) transporting the lean liquid treated in step B) to a lean liquid cooler for cooling; D) conveying the cooled lean liquid to a precision filter for filtration; E) transporting the filtered lean liquid to a solvent purification device to separate the heat-stable salt, and the separated lean liquid is reused in the carbon dioxide capture system.

2. The amine liquid purification method according to claim 1, characterized in that: In step A), in the lean solution after desorption, the mass content of the heat-stable salt is 1.0% to 1.5%, and the molar ratio of the amine to CO2 is 1:0.15 to 0.

25.

3. The amine liquid purification method according to claim 1, characterized in that: In step B), the partial lean liquid after desorption accounts for 1% to 10% of the mass of the total lean liquid after desorption.

4. The amine liquid purification method according to claim 1, characterized in that: In step B), after separation of CO2, the molar ratio of amine to CO2 in the obtained lean liquid is 1:0.03-0.

07.

5. The amine liquid purification method according to claim 1, characterized in that: In step C), the temperature of the cooled lean solution is 20-30°C.

6. The amine liquid purification method according to claim 1, characterized in that: In step D), the filtration accuracy is 5 to 10 μm.

7. The amine liquid purification method according to claim 1, characterized in that: In step E), the solvent purification device is an electrodialysis device, and the membrane parameters include: thickness 150 μm, resistance 1.9 Ω·cm 2 , bursting strength>0.5Mpa, operating temperature 25~40℃, operating pH 2~10.

8. The amine liquid purification method according to claim 1, characterized in that: In step E), the solvent purification device may also be an ion resin exchange device, and the parameters of the ion resin exchange device include: The resin parameter is 1.35mmol·mL -1 , operating temperature 25-40℃, operating pH 2-10.

9. An amine liquid purification system for a carbon dioxide capture system, comprising: Regeneration tower; A residual CO2 removal device connected to the lean liquid outlet of the regeneration tower; a lean liquid cooler connected to the lean liquid outlet of the excess CO2 removal device; A precision filter connected to the lean liquid outlet of the lean liquid cooler; A solvent purification device connected to the lean liquid outlet of the precision filter.

10. The amine liquid purification system according to claim 9, characterized in that: The lean liquid outlet of the solvent purification device is connected to a carbon dioxide capture system.

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