Device for capturing carbon dioxide in flue gas by using mixed alcohol amine method

Abstract

The utility model provides a device for capturing flue gas carbon dioxide by using a mixed alcohol amine method, which overcomes the defects of huge equipment energy consumption, lower efficiency and low concentration of captured carbon dioxide when the existing mixed alcohol amine method is used for capturing carbon dioxide. On the basis of a mixed alcohol amine method, the carbon dioxide can be efficiently captured by adopting a device design concept of high-pressure absorption, normal-pressure regeneration and pressurized regeneration, so that the concentration of the obtained carbon dioxide is higher, and the regeneration rate of the carbon dioxide can be accelerated; according to the device, the semi-pregnant solution of the normal-pressure regeneration tower and the pressurized regeneration tower is introduced into the absorption tower, so that the energy consumption of the device can be reduced, higher heat efficiency can be achieved, the circulation is faster, the operation efficiency of the whole device can be improved, and the device shows higher reliability and stability in actual industrial application and can be continuously operated for a long time.

Description

Technical Field

[0001] The utility model belongs to the technical field of carbon dioxide gas capture, and specifically relates to a device for capturing flue gas carbon dioxide using a mixed alcohol amine method. Background Art

[0002] With the development of human economy and society, carbon dioxide emissions caused by activities such as burning fossil fuels have continued to increase, becoming one of the main causes of global climate change and environmental pollution. In order to reduce such emissions and meet the requirements of environmental protection regulations, various carbon dioxide capture technologies have been widely studied and applied. At present, the commonly used technical means for carbon dioxide capture include chemical absorption, physical absorption, physical adsorption, membrane separation, and condensation.

[0003] Among them, the mixed alcohol amine method, as a chemical absorption method, is one of the most widely used carbon dioxide capture technologies at present; its principle is to use a specific alcohol amine solution (such as methanolamine, ethanolamine, etc.) to react chemically with carbon dioxide in the flue gas to absorb carbon dioxide from the gas flow. The process flow of the mixed alcohol amine method usually includes the absorption of carbon dioxide, the regeneration of the alcohol amine solution, and the recycling of carbon dioxide. During the absorption process, the flue gas contacts the alcohol amine solution through the absorption tower, and the carbon dioxide is absorbed to form a carbon dioxide alcohol amine solution; then the alcohol amine solution containing carbon dioxide enters the desorption tower through the heat exchanger to desorb carbon dioxide from the alcohol amine solution, and the regenerated alcohol amine solution is used for the next round of carbon dioxide absorption. The captured carbon dioxide can be compressed, transported or stored for enhanced oil extraction or industrial production, thereby achieving the purpose of reducing greenhouse gas emissions. Although the mixed alcohol amine method has certain advantages in the field of carbon dioxide capture, it also faces some challenges, such as: the energy consumption of the equipment is huge when capturing carbon dioxide, the efficiency is low, and the concentration of captured carbon dioxide is not very high.

[0004] In view of the above problems, the present invention considers that it is necessary to optimize and improve the device for capturing carbon dioxide using the mixed alcohol amine method. Summary of the invention

[0005] The utility model aims to solve the shortcomings of the existing mixed alcohol amine method in capturing carbon dioxide, such as huge equipment energy consumption, low efficiency and low concentration of captured carbon dioxide, and to provide a device for capturing flue gas carbon dioxide by the mixed alcohol amine method.

[0006] To achieve the above purpose, the technical solution provided by the utility model is:

[0007] A device for capturing flue gas carbon dioxide by a mixed alcohol amine method, which is special in that it comprises a pretreatment unit, an absorption tower, a normal pressure regeneration tower, a pressurized regeneration tower, a pressurized cooling unit, a first solution treatment unit, a second solution treatment unit, a first gas treatment unit, a second gas treatment unit and a lean amine supply unit;

[0008] The pretreatment unit is used to cool down and preliminarily separate the flue gas, and includes a first cooler and a separator along the flow direction of the flue gas;

[0009] The flue gas output by the pretreatment unit is pressurized and cooled by the pressurized cooling unit and then flows to the absorption tower (the purpose of setting the pressurized cooling unit here is to reduce the temperature of the flue gas again before the flue gas enters the absorption tower, and the pressure is increased; low temperature is conducive to the mixed alcohol amine solution to absorb carbon dioxide, and sufficient gas pressure can improve the absorption efficiency of carbon dioxide); the pressurized cooling unit includes a pressurizer and a second cooler along the flow direction of the flue gas;

[0010] The absorption tower is provided with a solution outlet I at the bottom, and a flue gas inlet is provided near the bottom; the absorption tower is provided with a first packing area, a first sprayer, a second packing area and a second sprayer from bottom to top; the arrangement of the packing area can prolong the retention time of the mixed alcohol amine solution in the absorption tower, so that the mixed alcohol amine solution can fully contact with the flue gas, thereby improving the absorption efficiency;

[0011] The rich liquid flowing out of the bottom of the absorption tower flows to the atmospheric regeneration tower through the first solution treatment unit; the first solution treatment unit includes a flash tank, a second pump, a first lean-rich liquid exchanger and a fifth pump in the flow direction;

[0012] The top of the atmospheric regeneration tower is connected to the first gas processing unit, a solution inlet I is arranged near the top, and a solution outlet II is arranged at the bottom; a third sprayer, a third packing area, a first liquid accumulation tray, a fourth sprayer and a fourth packing area are arranged in sequence from top to bottom in the atmospheric regeneration tower; wherein the first liquid accumulation tray is used to hold the solution passing through the third packing area, and the solution is a semi-rich solution; the solution inlet I is connected to the third sprayer;

[0013] The solution flowing out of the bottom of the atmospheric regeneration tower is divided into two paths after passing through the first reboiler, one path flows back to the fourth sprayer, and the other path flows to the pressurized regeneration tower through the second solution treatment unit; the second solution treatment unit includes a second lean-rich liquid exchanger and a pump seven in sequence along the flow direction;

[0014] The top of the pressurized regeneration tower (the pressurized regeneration tower has the ability to control the pressure in the tower) is connected to the second gas processing unit, and a solution inlet II is provided near the top; a solution outlet III is provided at the bottom; the pressurized regeneration tower is provided with a fifth sprayer, a fifth packing area, a second liquid accumulation tray, a sixth sprayer and a sixth packing area from top to bottom; wherein the second liquid accumulation tray is used to hold the solution passing through the fifth packing area, and the solution is a semi-rich solution; the solution inlet II is connected to the fifth sprayer;

[0015] The solution flowing out of the bottom of the pressurized regeneration tower is divided into two paths after passing through the second reboiler, one path is refluxed to the sixth sprayer, and the other path is sequentially passed through the second lean-rich liquid exchanger, pump four, and the first lean-rich liquid exchanger to flow back to the lean amine supply unit;

[0016] The output of the lean amine supply unit is communicated with the first sprayer, and the lean amine supply unit includes an amine liquid storage tank, a pump 1 and a lean amine cooler in sequence along the flow direction;

[0017] The solutions on the first liquid accumulation tray and the second liquid accumulation tray flow back to the first sprayer through pump three and pump six respectively; because the first liquid accumulation tray and the second liquid accumulation tray contain semi-rich liquid, and the semi-rich liquid flows back to the absorption tower for absorption, it reaches absorption saturation faster than the lean liquid, which can accelerate the whole absorption-desorption process, so that the whole adsorption-desorption process can be circulated faster and better, reducing the energy consumption of the device and achieving higher thermal efficiency;

[0018] The first gas processing unit includes a third cooler and a first gas separator. After the regeneration gas from the atmospheric pressure regeneration tower enters the third cooler, it is separated under the action of the first gas separator to obtain pure CO2 and store it. The liquid obtained by the first gas separator is further refluxed to the atmospheric pressure regeneration tower through the third sprayer.

[0019] The second gas processing unit includes a fourth cooler and a second gas separator. After the regeneration gas of the pressurized regeneration tower enters the fourth cooler, it is separated under the action of the second gas separator to obtain pure CO2 and store it. The liquid obtained by the second gas separator is further refluxed to the pressurized regeneration tower through the fifth sprayer.

[0020] The atmospheric regeneration tower and the pressurized regeneration tower are both provided with a regeneration heat source.

[0021] Furthermore, a steam regeneration heat source with a pressure of 0.8 MPa is provided at the bottom of both the atmospheric pressure regeneration tower and the pressurized regeneration tower.

[0022] Furthermore, the amine liquid stored in the amine liquid storage tank is a mixture of ethanolamine and hexamethylenediamine (MEA-HMDA), that is, the mixture is used as the absorbent in the absorption tower, and the absorbent has a high absorption efficiency.

[0023] The advantages of the utility model are:

[0024] 1. The utility model is based on the mixed alcohol amine method and adopts the device design concept of high-pressure absorption-normal pressure regeneration-pressurized regeneration to efficiently capture carbon dioxide, so that the obtained CO2 concentration is higher and the regeneration rate of CO2 can be accelerated.

[0025] 2. The utility model introduces the semi-rich liquid of the atmospheric regeneration tower and the pressurized regeneration tower into the absorption tower, which can reduce the energy consumption of the device, achieve higher thermal efficiency, and cycle faster, thereby improving the operating efficiency of the entire device. It exhibits higher reliability and stability in actual industrial applications and can operate continuously for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The utility model is a structural schematic diagram of a device for capturing carbon dioxide from flue gas using a mixed alcohol amine method.

[0027] The reference numerals are as follows:

[0028] 1-first cooler, 2-separator, 3-pressurizer, 4-second cooler, 5-absorption tower, 51-first sprayer, 52-first packing area, 53-second sprayer, 54-second packing area, 6-lean amine cooler, 7-pump one, 8-amine liquid storage tank, 9-flash tank, 10-pump two, 11-first lean and rich liquid exchanger, 12-pump three, 13-pump four, 14-pump five, 15-normal pressure regeneration tower, 151-third sprayer, 152-third packing area, 153-first 1-liquid accumulation tray, 154-fourth sprayer, 155-fourth filling area, 16-third cooler, 17-first gas separator, 18-first reboiler, 19-pump six, 20-second lean-rich liquid exchanger, 21-pump seven, 22-pressurized regeneration tower, 221-fifth sprayer, 222-fifth filling area, 223-second liquid accumulation tray, 224-sixth sprayer, 225-sixth filling area, 23-fourth cooler, 24-second gas separator, 25-second reboiler. DETAILED DESCRIPTION

[0029] The following is a further detailed description of the present invention in conjunction with the accompanying drawings and specific embodiments:

[0030] like Figure 1 As shown, the utility model is a device for capturing flue gas carbon dioxide by a mixed alcohol amine method, comprising a pretreatment unit, an absorption tower, a normal pressure regeneration tower, a pressurized regeneration tower, a pressurized cooling unit, a first solution treatment unit, a second solution treatment unit, a first gas treatment unit, a second gas treatment unit and a lean amine supply unit; the entire device uses a mixture of ethanolamine and hexamethylenediamine with relatively high absorption efficiency stored in the lean amine supply unit as an absorbent.

[0031] The pretreatment unit is used to cool down and preliminarily separate the flue gas, and it includes a first cooler and a separator along the flow direction of the flue gas; the flue gas output by the pretreatment unit is pressurized and cooled by the pressurized cooling unit and then flows to the absorption tower; the pressurized cooling unit includes a pressurizer and a second cooler along the flow direction of the flue gas.

[0032] A solution outlet I is arranged at the bottom of the absorption tower, and a flue gas inlet is arranged near the bottom; a first filler area, a first sprayer, a second filler area and a second sprayer are arranged in sequence from bottom to top in the absorption tower.

[0033] The rich liquid flowing out from the bottom of the absorption tower flows to the atmospheric pressure regeneration tower through the first solution treatment unit; the first solution treatment unit includes a flash tank, pump two, a first lean-rich liquid exchanger and pump five in the flow direction.

[0034] The top of the atmospheric regeneration tower is connected to the first gas processing unit, a solution inlet I is arranged near the top, and a solution outlet II is arranged at the bottom; a third sprayer, a third packing area, a first liquid accumulation tray, a fourth sprayer and a fourth packing area are arranged in sequence from top to bottom in the atmospheric regeneration tower; wherein the first liquid accumulation tray is used to hold the solution passing through the third packing area; the solution inlet I is connected to the third sprayer;

[0035] The lean liquid flowing out of the bottom of the atmospheric regeneration tower is divided into two paths after passing through the first reboiler, one path is refluxed to the fourth sprayer, and the other path flows to the pressurized regeneration tower through the second solution treatment unit; the second solution treatment unit includes a second lean-rich liquid exchanger and pump seven in sequence along the flow direction.

[0036] The top of the pressurized regeneration tower is connected to the second gas processing unit, and a solution inlet II is arranged near the top; a solution outlet III is arranged at the bottom; the pressurized regeneration tower is provided with a fifth sprayer, a fifth packing area, a second liquid accumulation tray, a sixth sprayer and a sixth packing area from top to bottom; wherein the second liquid accumulation tray is used to hold the solution passing through the fifth packing area; the solution inlet II is connected to the fifth sprayer;

[0037] The solution flowing out of the bottom of the pressurized regeneration tower is divided into two paths after passing through the second reboiler, one path flows back to the sixth sprayer, and the other path flows back to the lean amine supply unit through the second lean-rich liquid exchanger, pump four, and the first lean-rich liquid exchanger in sequence;

[0038] The output of the lean amine supply unit is communicated with the first sprayer, and the lean amine supply unit includes an amine liquid storage tank, a pump 1 and a lean amine cooler in sequence along the flow direction;

[0039] The solutions on the first liquid accumulation tray and the second liquid accumulation tray are pumped back to the first sprayer through pump three and pump six respectively;

[0040] The first gas processing unit includes a third cooler and a first gas separator. After the regeneration gas from the atmospheric pressure regeneration tower enters the third cooler, it is separated under the action of the first gas separator to obtain pure CO2 and store it. The liquid obtained by the first gas separator is further refluxed to the atmospheric pressure regeneration tower through the third sprayer.

[0041] The second gas processing unit includes a fourth cooler and a second gas separator. After the regeneration gas from the pressurized regeneration tower enters the fourth cooler, it is separated under the action of the second gas separator to obtain pure CO2 and store it. The liquid obtained from the second gas separator is further refluxed to the pressurized regeneration tower through the fifth sprayer.

[0042] The normal pressure regeneration tower and the pressurized regeneration bottom are both equipped with a steam regeneration heat source with a pressure of 0.8 MPa, which is used to heat the solution to desorb carbon dioxide.

[0043] The device uses a lean and rich liquid exchanger in order to achieve thermal energy balance between the liquids. Since the lean liquid temperature is low and the rich liquid temperature is high, the lean liquid and the rich liquid exchange heat in the heat exchanger, causing the lean liquid temperature to increase and the rich liquid temperature to decrease.

[0044] The working process is as follows:

[0045] The flue gas enters the first cooler 1 for cooling and then enters the gas separator 2 for preliminary separation. The obtained flue gas enters the pressurizer 3 for pressurization and then passes through the second cooler 4 for cooling before entering the lower end of the absorption tower 5. The flue gas flows upward and countercurrently contacts with the absorbent flowing from top to bottom in the first packing area 52 (when the device starts to operate, the absorbent only comes from the mixed alcohol amine solution provided by the lean amine supply unit after passing through the second packing area. After running for a period of time, it also comes from the semi-rich liquid of the first spray device 51). The absorbent absorbs most of the CO2 in the flue gas. The flue gas continues to rise and countercurrently contacts with the lean liquid flowing from top to bottom from the second sprayer 53 in the second packing area 54. The lean liquid further absorbs the CO2 in the flue gas. The rich liquid obtained at the bottom of the absorption tower 5 enters the flash pump 9 for flash evaporation to reduce the pressure of the gas, and then passes through the first lean-rich liquid exchanger 11 under the action of the pump 2 10, and then in The rich liquid enters the top of the atmospheric regeneration tower 15 under the action of the pump 5 14; the rich liquid flows downward through the third sprayer 151 in the heated atmospheric regeneration tower 15, contacts the third packing area 152, a part of the gas is regenerated and enters the third cooler 16, and is separated under the action of the first gas separator 17 to obtain pure CO2, the liquid obtained by the first gas separator 17 further enters the top of the atmospheric regeneration tower 15 and continues to fully contact with the third packing area 152; a part of the semi-rich liquid flowing out of the third packing area 152 enters the first liquid accumulation tray 153, and the other part continues to flow downward and fully contacts with the fourth packing area 155, the regenerated CO2 gas enters the top of the atmospheric regeneration tower 15, A part of the solution flowing into the bottom is refluxed to the fourth sprayer 154 under the action of the first reboiler 18 to continue to contact with the fourth packing area 155 to regenerate CO2; the other part enters the heated pressurized regeneration tower 22 to continue to regenerate CO2; the liquid is fully contacted with the fifth packing area 222 through the fifth sprayer 221, and a part of the gas is regenerated and enters the second cooler 23, and is separated to obtain pure CO2 under the action of the second gas separator 24. The liquid obtained by the second gas separator 24 further enters the top of the pressurized regeneration tower 22 and continues to fully contact with the fifth packing area 221; a part of the solution flowing out of the fifth packing area 222 of the pressurized regeneration tower enters the second liquid accumulation tray 223, and the other part of the solution flows out of the fifth packing area 222 of the pressurized regeneration tower. A part of it continues to flow downward and fully contacts with the sixth filling area 225, and the regenerated CO2 gas enters the top of the pressurized regeneration tower 22. Under the action of the second reboiler 25, a part of the solution flowing into the bottom enters the sixth sprayer 224 to continue to contact with the sixth filling area 225 to regenerate CO2, and the other part passes through the second lean-rich liquid exchanger 20 and the first lean-rich liquid exchanger 11 in sequence under the action of pump four 13 and is stored in the amine liquid storage tank 8. The lean amine liquid passes through the lean amine cooler 6 and enters the second sprayer 53 of the absorption tower 5 again; the semi-rich liquid in the liquid accumulation tray in the atmospheric pressure regeneration tower 15 and the pressurized regeneration tower 22 passes through pump three 12 and pump six 19 respectively and enters the first sprayer 51 of the absorption tower 5.

[0046] The above process completes a cycle of capturing carbon dioxide from flue gas. Repeating the above process can achieve the fixation and conversion of carbon dioxide from flue gas.

[0047] The device for capturing flue gas carbon dioxide designed with the idea of ​​high-pressure absorption-normal-pressure regeneration-pressurized regeneration can capture carbon dioxide efficiently, and can usually achieve a carbon dioxide removal efficiency of more than 90%. When the adsorbent is saturated and needs to be regenerated, the adsorbent in the adsorption tower will be transferred to the regeneration tower. In the regeneration tower, the target substance carbon dioxide will be desorbed from the adsorbent by heating or other methods, making the adsorbent active again. Introducing the semi-rich liquid from the normal-pressure regeneration tower and the pressurized regeneration tower into the absorption tower can not only reduce the energy consumption of the device, but also achieve higher thermal efficiency.

[0048] The above description is only a specific implementation mode of the present utility model, but the protection scope of the present utility model is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed in the present utility model, and these modifications or substitutions should be included in the protection scope of the present utility model.

Claims

1. A device for capturing flue gas carbon dioxide using a mixed alcohol amine method, characterized in that: It includes a pretreatment unit, an absorption tower, a normal pressure regeneration tower, a pressurized regeneration tower, a pressurized cooling unit, a first solution treatment unit, a second solution treatment unit, a first gas treatment unit, a second gas treatment unit and a lean amine supply unit; The pretreatment unit is used to cool down and preliminarily separate the flue gas, and includes a first cooler and a separator along the flow direction of the flue gas; The flue gas outputted by the pretreatment unit is pressurized and cooled by the pressurized cooling unit and then flows to the absorption tower; the pressurized cooling unit includes a pressurizer and a second cooler along the flue gas flow direction; The absorption tower is provided with a solution outlet I at the bottom, and a flue gas inlet is provided near the bottom; The absorption tower is provided with a first filler area, a first sprayer, a second filler area and a second sprayer from bottom to top; The rich liquid flowing out from the bottom of the absorption tower flows to the atmospheric regeneration tower through the first solution treatment unit; the first solution treatment unit includes a flash tank, a second pump, a first lean-rich liquid exchanger and a fifth pump in the flow direction; The top of the atmospheric regeneration tower is connected to the first gas processing unit, a solution inlet I is arranged near the top, and a solution outlet II is arranged at the bottom; a third sprayer, a third packing area, a first liquid accumulation tray, a fourth sprayer and a fourth packing area are arranged in sequence from top to bottom in the atmospheric regeneration tower; wherein the first liquid accumulation tray is used to hold the solution passing through the third packing area; the solution inlet I is connected to the third sprayer; The solution flowing out of the bottom of the atmospheric regeneration tower is divided into two paths after passing through the first reboiler, one path flows back to the fourth sprayer, and the other path flows to the pressurized regeneration tower through the second solution treatment unit; the second solution treatment unit includes a second lean-rich liquid exchanger and a pump seven in sequence along the flow direction; The top of the pressurized regeneration tower is connected to the second gas processing unit, and a solution inlet II is arranged near the top; a solution outlet III is arranged at the bottom; a fifth sprayer, a fifth packing area, a second liquid accumulation tray, a sixth sprayer and a sixth packing area are arranged in the pressurized regeneration tower from top to bottom; wherein the second liquid accumulation tray is used to hold the solution passing through the fifth packing area; the solution inlet II is connected to the fifth sprayer; The solution flowing out of the bottom of the pressurized regeneration tower is divided into two paths after passing through the second reboiler, one path is refluxed to the sixth sprayer, and the other path is sequentially passed through the second lean-rich liquid exchanger, pump four, and the first lean-rich liquid exchanger to flow back to the lean amine supply unit; The output of the lean amine supply unit is communicated with the first sprayer, and the lean amine supply unit includes an amine liquid storage tank, a pump 1 and a lean amine cooler in sequence along the flow direction; The solutions on the first liquid accumulation tray and the second liquid accumulation tray flow back to the first sprayer through pump three and pump six respectively; The first gas processing unit includes a third cooler and a first gas separator. After the regeneration gas from the atmospheric pressure regeneration tower enters the third cooler, it is separated under the action of the first gas separator to obtain pure CO2 and store it. The liquid obtained by the first gas separator is further refluxed to the atmospheric pressure regeneration tower through the third sprayer. The second gas processing unit includes a fourth cooler and a second gas separator. After the regeneration gas of the pressurized regeneration tower enters the fourth cooler, it is separated under the action of the second gas separator to obtain pure CO2 and store it. The liquid obtained by the second gas separator is further refluxed to the pressurized regeneration tower through the fifth sprayer. The atmospheric regeneration tower and the pressurized regeneration tower are both provided with a regeneration heat source.

2. The device for capturing flue gas carbon dioxide using the mixed alcohol amine method according to claim 1, characterized in that: The bottoms of the atmospheric regeneration tower and the pressurized regeneration tower are both provided with a steam regeneration heat source with a pressure of 0.8 MPa.

3. The device for capturing flue gas carbon dioxide using the mixed alcohol amine method according to claim 2, characterized in that: The amine liquid stored in the amine liquid storage tank is a mixture of ethanolamine and hexamethylenediamine.

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