Dynamic phase-splitting carbon dioxide capture system based on phase change absorbent and method of carbon dioxide capture

Abstract

The application provides a dynamic phase separation carbon dioxide capture system and method. The system comprises a connected absorption tower, coalescing device, centrifugal phase separator, mixing tank and desorption tower, wherein the absorption tower is internally capable of being connected to a phase change absorbent, the mixed absorbent outlet of the absorption tower is connected to the mixed absorbent inlet of the coalescing device; the coalescing device is internally provided with coalescing fillers, and the coalescing product outlet of the coalescing device is connected to the coalescing product inlet of the centrifugal phase separator; the lean phase solution outlet of the centrifugal phase separator is connected to the lean phase solution inlet of the mixing tank, and the rich phase solution outlet of the centrifugal phase separator is connected to the rich phase solution inlet of the desorption tower through a heat exchanger; the regenerated absorbent outlet of the desorption tower is connected to the regenerated absorbent inlet of the mixing tank through a heat exchanger; the mixing tank is used for mixing the regenerated absorbent and the lean phase solution in the mixing tank to obtain a mixed absorbent, and the mixed absorbent outlet of the mixing tank is connected to the phase change absorbent inlet of the absorption tower.

Description

Technical Field

[0001] This invention relates to a dynamic phase separation system and method for carbon dioxide capture based on a phase change absorbent, and particularly to an industrial flue gas carbon dioxide capture system and method based on a phase change absorbent, belonging to the field of carbon dioxide capture technology. Background Technology

[0002] The massive emissions of greenhouse gases, primarily carbon dioxide (CO2), have caused a series of climate change problems, including sea-level rise, glacial melting, and frequent extreme weather events, drawing widespread international attention. Chemical absorption methods using organic amine solutions as absorbents offer advantages such as rapid absorption rates, high selectivity, and mature processes, making them suitable for carbon capture of flue gas at near-atmospheric pressure, high flow rates, and relatively low CO2 concentrations (3-20%). However, the regeneration process of amine-based absorbents requires a large amount of high-grade steam, and effective regeneration can only be achieved quickly at desorption temperatures exceeding 110°C. This results in a high regeneration heat load for existing absorbents, which is the main reason for the excessively high capture costs.

[0003] In recent years, to address the issue of high regeneration energy consumption during desorption, researchers have proposed the concept of phase change absorption. Under certain conditions, the solution after CO2 absorption undergoes phase separation, with CO2-related components concentrated in one phase (rich phase) and the other phase (lean phase) dominated by phase-separating agents with low CO2 loading. During desorption, only the rich phase needs to be regenerated, significantly reducing the volume of the regenerated liquid and thus effectively improving the efficiency of steam thermal energy utilization. Researchers both domestically and internationally have developed a series of phase change absorbents with CO2 loadings exceeding 2.5 mol / L, a rich liquid volume ratio of 50%-60%, and regeneration heat consumption reduced to 2.0-2.4 GJ / t CO2, demonstrating significant energy-saving potential.

[0004] However, existing research mainly focuses on testing and evaluating the phase separation effect of phase change absorbents under static conditions (including critical phase separation loading, phase separation time / volume ratio, phase separation efficiency, etc.). The results of these studies cannot meet the design requirements of phase separation processes in actual carbon capture systems under circulating absorbent conditions, and the flow state inevitably interferes with the phase separation process. Therefore, developing efficient dynamic phase separation systems for phase change absorbents is crucial for their industrial application.

[0005] Reference 1 discloses a carbon dioxide capture system and method for blast furnace gas based on phase change absorbent. This system includes a pretreatment device, an absorption tower, a phase separator, a stripping tower, and a lean-rich liquid heat exchanger. It uses an amine-based phase change absorbent to capture carbon dioxide in blast furnace gas. However, the reference does not clearly explain the structure and working principle of its phase separator, but only provides a schematic diagram of a phase separator with "one inlet and two outlets". This structure cannot effectively avoid the interference of continuous absorbent flow on the weak phase separation process.

[0006] Reference 2 discloses a flue gas carbon dioxide capture system based on phase change absorbent. This system includes a high-temperature absorption tower, a low-temperature absorption tower, a first phase separator, a second phase separator, and a lean-rich liquid heat exchanger. It uses an amine-based phase change absorbent to capture carbon dioxide in blast furnace gas. However, the reference does not clearly explain the structure and working principle of the first and second phase separators. Observing its schematic diagram, it can be seen that the two phase separators are both located inside the absorption tower (at the bottom of the tower), and the separation of lean and rich phases is achieved through vertical baffles and gravity.

[0007] Reference 3 discloses a method for enhancing phase separation of phase change absorbents, providing a method to accelerate the phase separation process by enhancing the absorption of CO2 products and phase separation agent components by organic amines in the absorbent using magnetic fields and ultrasound. However, the universality and economic efficiency of using external fields such as magnetic fields and sound waves to enhance phase separation still need further investigation.

[0008] Therefore, researching a dynamic phase separation system and method for carbon dioxide capture based on phase change absorbents has become an urgent technical problem to be solved.

[0009] References:

[0010] Reference 1: CN116850751A

[0011] Reference 2: CN108187455A

[0012] Reference 3: CN112295363A Summary of the Invention

[0013] The problem the invention aims to solve

[0014] In view of the technical problems existing in the prior art, the purpose of this application is to provide a dynamic phase separation system for carbon dioxide capture based on phase change absorbent. The system uses a coalescing packing coupled with centrifugal phase separation technology, which enables the phase change absorbent to achieve efficient phase separation and give full play to its advantages of low energy consumption regeneration.

[0015] The present invention also provides a carbon dioxide capture method, which is simple and easy to operate, saves energy, and has excellent versatility and economy.

[0016] Solution for solving the problem

[0017] [1] A dynamic phase-separated carbon dioxide capture system, comprising an absorption tower, a coalescing device, a centrifugal phase separator, a mixing tank, and a desorption tower connected in series, wherein,

[0018] The absorption tower can be filled with a phase change absorbent, and the outlet of the mixed absorbent liquid of the absorption tower is connected to the inlet of the mixed absorbent liquid of the coalescence device.

[0019] The coalescing device is equipped with coalescing packing, and the coalescing product outlet of the coalescing device is connected to the coalescing product inlet of the centrifugal phase separator.

[0020] The lean phase solution outlet of the centrifugal phase separator is connected to the lean phase solution inlet of the mixing tank, and the rich phase solution outlet of the centrifugal phase separator is connected to the rich phase solution inlet of the desorption tower via a heat exchanger.

[0021] The regenerated absorbent outlet of the analytical column is connected to the regenerated absorbent inlet of the mixing tank via the heat exchanger;

[0022] The mixing tank is used to mix the regenerated absorbent with the lean phase solution in the mixing tank to obtain a mixed absorbent, and the mixed absorbent outlet of the mixing tank is connected to the phase change absorbent inlet of the absorption tower.

[0023] [2] According to the dynamic phase-separated carbon dioxide capture system described in [1] above, an interstage cooling device is also provided between the absorber packing layers inside the absorber tower to cool down the gaseous substances generated during the absorption of carbon dioxide in the absorber tower.

[0024] An absorption tower demister is installed at the top of the absorption tower.

[0025] [3] According to the dynamic phase-separated carbon dioxide capture system described in [1] or [2] above, wherein the phase change absorbent includes a composite organic amine phase change absorbent, preferably, the composite organic amine phase change absorbent includes organic amine, phase separation agent and water.

[0026] [4] The dynamic phase-separated carbon dioxide capture system according to any one of [1]-[3] above, wherein the coalescing filler is derived from fiber material; preferably, the fiber material includes one or more of stainless steel fiber, nylon fiber, polytetrafluoroethylene fiber, and glass fiber.

[0027] [5] The dynamic phase-separated carbon dioxide capture system according to any one of [1]-[4] above, wherein the coalescing device is provided with a coalescing device insulation layer outside the coalescing device.

[0028] [6] The dynamic phase-separated carbon dioxide capture system according to any one of [1]-[5] above, wherein the mixing tank is equipped with a stirring device, and / or the mixing tank is also provided with a phase change absorbent replenishment port.

[0029] [7] The dynamic phase-separated carbon dioxide capture system according to any one of [1]-[5] above, wherein the top of the desorption tower is provided with one or both of a desorption tower demister and a condenser; and / or the bottom of the desorption tower is provided with a reboiler;

[0030] Preferably, the outer layer of the analytical tower is provided with an analytical tower insulation layer.

[0031] [8] A carbon dioxide capture method, comprising the following steps:

[0032] Flue gas is conveyed to an absorption tower, and a phase change absorbent is introduced into the absorption tower; in the absorption tower, the phase change absorbent absorbs carbon dioxide in the flue gas and generates a mixed absorbent liquid.

[0033] The agglomeration product obtained after the mixed absorbent is processed by the agglomeration device is transported to the centrifugal phase separator, and the agglomeration product is separated by the centrifugal phase separator to obtain a rich phase solution and a poor phase solution.

[0034] The lean phase solution is transported to a mixing tank, and the rich phase solution is transported to a desorption tower via a heat exchanger for desorption treatment to obtain a regenerated absorbent;

[0035] The regenerated absorbent is transported via the heat exchanger to the mixing tank and mixed with the lean phase solution to obtain a mixed absorbent.

[0036] Optionally, the mixed absorbent is conveyed to an absorption tower for absorbing carbon dioxide from flue gas.

[0037] [9] According to the carbon dioxide capture method described in [8] above, wherein the residence time of the mixed absorbent in the coalescence device is 10-120 s; and / or,

[0038] The temperature at which the coalesced products enter the centrifugal phase separator is 40-60°C; and / or,

[0039] The centrifugal phase separator rotates at a speed of 1000-8000 r / min; and / or,

[0040] The flow rate of the rich phase solution delivered to the stripping column is 40-80% of the flow rate of the coalescing product, and the flow rate of the lean phase solution delivered to the mixing tank is 20-60% of the flow rate of the coalescing product.

[0041]

[10] According to the carbon dioxide capture method described in [8] or [9] above, the residence time of the lean phase solution and / or the regenerated absorbent in the mixing tank is 30-60s; and / or the rotation speed of the stirring device of the mixing tank is 30-200r / min.

[0042] The effects of the invention

[0043] The carbon dioxide capture dynamic phase separation system of the present invention adopts the technology of coalescing packing coupled with centrifugal phase separation, which can achieve efficient phase separation of phase change absorbent and give full play to its advantages of low energy consumption regeneration.

[0044] The carbon dioxide capture method of the present invention is simple and easy to operate, saves energy, and has excellent versatility and economy. Attached Figure Description

[0045] Figure 1 A schematic diagram of the flow structure of the carbon dioxide capture dynamic phase separation system of the present invention is shown;

[0046] Figure 2 A schematic diagram of the centrifugal phase separation device of the present invention is shown;

[0047] Figure 3 A schematic diagram of the coalescence device of the present invention is shown;

[0048] Figure 4 The image shows a comparison of electron microscope (EM) images of the phase change absorbent of Example 1 before and after passing through the coalescence device. The left image is an EEM image before passing through the coalescence device, and the right image is an EEM image after passing through the coalescence device. Figure 5 The results of centrifugal phase separation tests on the five phase change absorbents of Example 2 are shown in the figure.

[0049] Explanation of reference numerals in the attached figures

[0050] 1: Absorption tower; 2: Coalescing device; 3: Centrifugal phase separator; 4: Heat exchanger;

[0051] 5: Mixing tank; 6: Desorption tower; 11: Interstage cooling device; 12: Absorber tower demister;

[0052] 13: Absorption tower packing layer; 21: Coalescing packing; 22: Coalescing device insulation layer;

[0053] 31: Inlet of the centrifugal phase separator for aggregated products; 32: Outlet of the centrifugal phase separator for lean phase solution;

[0054] 33: Rich phase solution outlet of the centrifugal phase separator; 51: Stirring device;

[0055] 52: Phase change absorbent replenishment port; 61: Demister of the stripping tower; 62: Condenser; 63: Reboiler;

[0056] 64: Insulation layer of the desorption tower; 65: Packing layer of the desorption tower; 81, 82: Circulation pump. Detailed Implementation

[0057] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0058] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0059] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0060] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0061] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0062] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0063] It is understood that the term "connection" as used in this specification may include direct connections between devices or indirect connections through pipes, conveyors (e.g., pumps), or other means.

[0064] <First Aspect>

[0065] like Figure 1 As shown, a first aspect of the present invention provides a dynamic phase-separated carbon dioxide capture system, comprising an absorption tower 1, a coalescing device 2, a centrifugal phase separator 3, a desorption tower 6, and a mixing tank 5 connected in series, wherein...

[0066] The absorption tower 1 can be filled with a phase change absorbent, and the outlet of the mixed absorbent liquid of the absorption tower 1 is connected to the inlet of the mixed absorbent liquid of the coalescence device 2.

[0067] The coalescing device 2 is equipped with coalescing packing 21, and the coalescing product outlet of the coalescing device 2 is connected to the coalescing product inlet 31 of the centrifugal phase separator 3.

[0068] The lean phase solution outlet 32 ​​of the centrifugal phase separator 3 is connected to the lean phase solution inlet of the mixing tank 5, and the rich phase solution outlet 33 of the centrifugal phase separator 3 is connected to the rich phase solution inlet of the desorption tower 6 via the heat exchanger 4.

[0069] The regenerated absorbent outlet of the analytical tower 6 is connected to the regenerated absorbent inlet of the mixing tank 5 via the heat exchanger 4;

[0070] The mixing tank 5 is used to mix the regenerated absorbent with the lean phase solution in the mixing tank 5 to obtain a mixed absorbent, and the mixed absorbent outlet of the mixing tank 5 is connected to the phase change absorbent inlet of the absorption tower 1.

[0071] The dynamic phase-separated carbon dioxide capture system of the present invention adopts the technology of coalescence device 2 coupled with centrifugal phase separator 3, which enables the phase-separated absorbent to be efficiently separated and give full play to its advantages of low energy consumption regeneration.

[0072] Absorption tower

[0073] Absorption tower 1 is a device for removing carbon dioxide from flue gas. A phase change absorbent can be introduced into the absorption tower 1 of this invention. The phase change absorbent of this invention can achieve carbon capture of carbon dioxide in the flue gas in the absorption tower 1 and produce a mixed absorbent containing carbon dioxide. The outlet of the absorption tower 1 of this invention is connected to the inlet of the coalescing device 2, specifically through a circulating pump 81 connected to the coalescing device 2.

[0074] Absorption tower 1 may include a flue gas inlet, a flue gas outlet, a phase change absorbent inlet, and a mixed absorbent outlet. The flue gas inlet is generally located at the bottom of absorption tower 1, allowing flue gas to flow in. The flue gas outlet is located at the top of absorption tower 1, allowing flue gas to flow out. The phase change absorbent inlet is located near the flue gas outlet, for allowing the phase change absorbent and / or mixed absorbent to flow in. The mixed absorbent outlet is located near the flue gas inlet, for discharging the mixed absorbent that has absorbed carbon dioxide. It is understood that the carbon dioxide content of the mixed absorbent is much higher than that of the regenerated absorbent.

[0075] In absorption tower 1, the aforementioned phase change absorbent and / or mixed absorbent flow from the top to the bottom of the tower, while the flue gas flows from the bottom to the top. This ensures that the flue gas flowing into absorption tower 1 comes into full countercurrent contact with the phase change absorbent and / or mixed absorbent. Carbon dioxide in the flue gas is absorbed by the phase change absorbent and / or mixed absorbent, forming a mixed absorbent liquid, which flows out from the mixed absorbent liquid outlet. Here, the carbon dioxide absorption rate is highest when the reaction temperature inside absorption tower 1 is between 40-70°C.

[0076] In some specific implementations, an absorption tower demister 12 is provided at the top of the absorption tower 1. The absorption tower demister 12 is generally composed of packing and wire mesh filling layer. The absorption tower demister 12 is used to separate the absorbent liquid carried in the flue gas after carbon capture, thereby reducing absorbent escape loss.

[0077] In some other specific embodiments, an interstage cooling device 11 is also provided between the absorber packing layers 13 inside the absorber tower 1 to cool down the gaseous substances generated during the absorption of carbon dioxide in the absorber tower 1.

[0078] Furthermore, the phase change absorbent of the present invention comprises a composite organic amine phase change absorbent. Preferably, the composite organic amine phase change absorbent comprises an organic amine, a phase-separating agent, and water (H2O). Based on the total mass of the composite organic amine phase change absorbent as 100%, the content of the organic amine is 20-50%, the content of the phase-separating agent is 30-70%, and the content of water is 20-50%.

[0079] This invention utilizes organic amines to increase the uptake capacity and rate of carbon dioxide. The organic amines comprise primary amines or their salts, secondary amines or their salts, tertiary amines or their salts, or quaternary amines or their salts. Preferably, the organic amines include one or more combinations of ethanolamine (MEA), diethanolamine (DEA), triethylamine (TEA), N,N-diethylethanolamine (DEEA), diallyltriamine (DPTA), methyldiethanolamine (MDEA), dimethylethanolamine (DMEA), tetramethyldiacetyltriamine (TMBPA), hydroxyethylethylenediamine (AEEA), pentamethyldiethylenetriamine (PMDTA), triethylenetetramine (TETA), dimethylaminopropylamine (DMAPA), N-methylpyrrolidone (NMP), isobutanolamine (AMP), diethylenetriamine (DETA), diisopropanolamine (DIPA), and piperazine (PZ).

[0080] This invention achieves the phase separation process of absorbed carbon dioxide by using a phase change phase-separating agent. In this invention, an aprotic polar solvent is used as the phase-separating agent. Specifically, the phase-separating agent includes one or a combination of two or more of polyethylene glycol dimethyl ether (NHD), dimethyl sulfoxide (DMSO), sulfolane (TMS), N,N-dimethylformamide (DMF), acetone (propanol), and 1,3-dimethyl-2-imidazolinone (IL).

[0081] coalescing device

[0082] The coalescence device 2 is internally equipped with coalescence packing 21. The coalescence device 2 of this invention includes a mixed absorbent inlet and a coalescence product outlet. When the phase change absorbent captures carbon dioxide, the organic amines in the solvent react with CO2 to generate products such as carbamates and protonated amines. These products have enhanced polarity and differ significantly from the phase-separating agent components in molecular structure and polarity, producing immiscible small droplets. This invention discovers that using coalescence packing 21, which has a polarity similar to the phase-separating agent, can accelerate the generation and growth of small droplets; larger droplets, under centrifugal force, aggregate and coalesce with components of similar density, achieving a rapid phase separation process. Specifically, the coalescence product outlet of the coalescence device 2 is connected to the coalescence product inlet 31 of the centrifugal phase separator 3.

[0083] In some specific embodiments, the coalescing filler 21 is derived from fibrous materials; preferably, the fibrous materials include one or more combinations of stainless steel fibers, nylon fibers, polytetrafluoroethylene fibers, and glass fibers.

[0084] Furthermore, a coalescing device insulation layer 22 is provided outside the coalescing device 2 to insulate the coalescing device 2 and reduce heat loss.

[0085] Centrifugal phase separator

[0086] The centrifugal phase separator 3 of the present invention is a device for separating the coalescing products after processing by the coalescing device 2. The centrifugal phase separator 3 of the present invention includes a coalescing product inlet 31, a rich phase solution outlet 33, and a lean phase solution outlet 32.

[0087] The centrifugal phase separator of the present invention can be used for phase separation of agglomeration products. The agglomeration products can be divided into a carbon dioxide-rich phase solution and a carbon dioxide-poor phase solution, wherein the main components of the rich phase solution are the product of the reaction between organic amine and carbon dioxide and water, and the main component of the poor phase solution is a phase separation absorbent.

[0088] In the centrifugal phase separator 3, due to the significant difference in molecular polarity among the components of the agglomerated products, phase separation occurs after processing. Generally, the upper layer is a lean phase with relatively low viscosity, and the lower layer is a rich phase with relatively high viscosity; more than 95% of the carbon dioxide can concentrate in the lower rich phase. The lean phase solution outlet 32 ​​of the centrifugal phase separator 3 is connected to the lean phase solution inlet of the mixing tank 5, and the rich phase solution outlet 33 of the centrifugal phase separator 3 is connected to the rich phase solution inlet of the desorption tower 6 via a heat exchanger 4.

[0089] Analytical Tower

[0090] The analytical column 6 and the centrifugal phase separator 3 of the present invention are connected for analyzing the rich phase solution to obtain a regenerated absorbent. The analytical column 6 of the present invention includes a rich phase solution inlet and a regenerated absorbent outlet. Specifically, the rich phase solution outlet 33 of the centrifugal phase separator 3 is connected to the rich phase solution inlet of the analytical column 6 via a heat exchanger 4.

[0091] This invention achieves carbon dioxide desorption by exchanging heat between the rich-phase solution and the heat exchange medium in the heat exchange flow path within the heat exchanger 4. Furthermore, by exchanging heat between the regenerated absorbent and the heat exchange medium in the heat exchange flow path, energy consumption in the heat exchange flow path is saved, and the carbon dioxide absorption capacity of the absorbent returning to the absorption tower 1 is increased. In addition, the heat exchange medium in the heat exchanger 4 can be either a gaseous medium or a liquid medium, wherein the gaseous medium can be water vapor, carbon dioxide, etc., and the liquid medium can be water, heat transfer oil, etc.

[0092] In some specific implementations, the top of the desorption tower 6 is provided with a desorption tower demister 61. The desorption tower demister 61 is generally composed of packing and a wire mesh packing layer. The desorption tower demister 61 of the present invention is used to separate absorbent droplets carried in the regeneration gas generated after desorption.

[0093] In some specific implementations, a condenser 62 is provided at the top of the stripping tower 6. The condenser 62 is used to condense the gaseous components generated after stripping to obtain a condensed gas phase composition and a condensed liquid phase composition. The condensed gas phase composition can be discharged from the stripping tower 6, and the condensed liquid phase composition can be recycled back into the stripping tower 6.

[0094] Furthermore, a reboiler 63 is provided at the bottom of the analytical column 6, which can be used to heat the absorbent with external steam and achieve thermal regeneration of the absorbent.

[0095] In some specific embodiments, the outer layer of the analytical tower 6 is provided with an analytical tower insulation layer 64, which can reduce heat loss. Additionally, in this invention, the interior of the analytical tower 6 may be provided with an analytical tower packing layer 65.

[0096] Mixing tank

[0097] The function of the mixing tank 5 of the present invention is to mix the lean phase solution with the regenerated absorbent after analysis. The mixing tank 5 of the present invention includes a lean phase solution inlet, a regenerated absorbent inlet, and a mixed absorbent outlet.

[0098] Specifically, the lean phase solution outlet of the centrifugal phase separator 3 is connected to the lean phase solution inlet of the mixing tank 5, allowing the lean phase solution to be transported to the mixing tank 5. The regeneration absorbent outlet of the desorption tower 6 is connected to the regeneration absorbent inlet of the mixing tank 5 via the heat exchanger 4, allowing the regeneration absorbent to be transported to the mixing tank 5, thereby mixing the lean phase solution and the regeneration absorbent in the mixing tank 5. Furthermore, the regeneration mixture outlet of the mixing tank 5 of the present invention is connected to the inlet of the absorption tower 1 via a circulation pump 82.

[0099] In some specific embodiments, the mixing tank 5 is equipped with a stirring device 51. Stirring allows the lean phase solution and the regenerated absorbent to mix more evenly in the mixing tank 5. Furthermore, to obtain the desired mixed absorbent, a phase change absorbent replenishment port 52 can be provided in the mixing tank 5 to replenish the phase change absorbent, so that the mixed absorbent in the mixing tank 5 can be used as the phase change absorbent in the absorption tower 1.

[0100] <Second aspect>

[0101] A second aspect of the present invention provides a carbon dioxide capture method, comprising the following steps:

[0102] Flue gas is conveyed to absorption tower 1, and a phase change absorbent is introduced into absorption tower 1; in absorption tower 1, the phase change absorbent absorbs carbon dioxide in the flue gas and generates a mixed absorbent liquid;

[0103] The agglomeration product of the mixed absorption liquid after being treated by the agglomeration device 2 is transported to the centrifugal phase separator 3, and the agglomeration product is separated by the centrifugal phase separator 3 to obtain a rich phase solution and a poor phase solution.

[0104] The lean phase solution is transported to the mixing tank 5, and the rich phase solution is transported to the desorption tower 6 via the heat exchanger 4 for desorption treatment to obtain the regenerated absorbent.

[0105] The regenerated absorbent is transported via the heat exchanger 4 to the mixing tank 5 and mixed with the lean phase solution to obtain a mixed absorbent.

[0106] Optionally, the mixed absorbent is conveyed to absorption tower 1 for absorbing carbon dioxide in flue gas.

[0107] The carbon dioxide capture method of the present invention is simple and easy to operate, saves energy, and has excellent versatility and economy.

[0108] In some specific embodiments, the residence time of the mixed absorbent in the coalescence device 2 is 10-120 s; the temperature of the coalescing product entering the centrifugal phase separator 3 is 40-60°C; the rotation speed of the centrifugal phase separator 3 is 1000-8000 r / min; the flow rate of the rich phase solution delivered to the desorption tower 6 is 40-80% of the flow rate of the coalescing product, and the flow rate of the lean phase solution delivered to the mixing tank 5 is 20-60% of the flow rate of the coalescing product.

[0109] In some specific embodiments, the residence time of the lean phase solution and / or the regeneration absorbent in the mixing tank 5 is 30-60 s; and / or, the rotation speed of the stirring device 51 of the mixing tank 5 is 30-200 r / min.

[0110] Example

[0111] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0112] Example 1

[0113] A coalescence apparatus test was conducted using a phase change absorber consisting of 30% DETA + 50% propanol + 20% H2O.

[0114] The coalescing device has a diameter of 0.3 meters, a length of 1.2 meters, and a packing zone length of 0.9 meters, and is composed of modified stainless steel fibers. The residence time of the absorbent in the coalescing device is 180 s, and the CO2 loading in the inlet absorbent is 1.47 mol / L. Electron micrographs are shown below. Figure 4 As shown, the number of small droplets of the phase change absorbent also increased significantly after passing through the coalescence device, and the size of the existing small droplets increased, with the average droplet diameter increasing at a rate of approximately 1.2 μm / min.

[0115] Example 2

[0116] Five phase change absorbents were selected for centrifugal phase separation testing: #1 (30% TMBPA + 50% NHD + 20% H2O), #2 (50% DEEA + 25% AEEA + 25% H2O), #3 (30% DETA + 50% propanol + 20% H2O), #4 (10% MEA + 20% DMEA + 50% TMS + 25% H2O), and #5 (25% DPTA + 5% MDEA + 15% IL + 35% TMS + 20% H2O).

[0117] The centrifugal phase separator includes an inlet and outlets for lean and rich phase solutions. The main structure of the centrifugal phase separator is made of metal and consists of inner and outer drums. The inner drum has a diameter of 60mm and a rotation speed of 1000-2000rpm, which can be adjusted via a frequency converter.

[0118] Phase separation test results are as follows: Figure 5 As shown, the critical phase separation loadings of the five absorbents are 1.29 mol / L, 1.28 mol / L, 1.08 mol / L, 1.36 mol / L and 0.81 mol / L, respectively. Once the critical point is exceeded, the absorbents will exhibit obvious phase separation behavior after passing through a centrifugal phase separator.

[0119] The mixed phase loading of absorbent #1 is 1.69 mol / L, the volumetric flow rate of the rich phase accounts for 74.2% of the total flow rate at the outlet of the phase separator, the volumetric flow rates of the lean phase solution and the rich phase solution are 0.08 L / min and 0.23 L / min, respectively, the CO2 loading of the lean phase solution and the rich phase solution are 1.23 mol / L and 3.66 mol / L, respectively, and the phase separation efficiency is 89.5%.

[0120] The mixed phase loading of absorbent #2 is 1.76 mol / L, the volumetric flow rate of the rich phase accounts for 48.6% of the total flow rate at the outlet of the phase separator, the volumetric flow rates of the lean phase solution and the rich phase solution are 0.18 L / min and 0.17 L / min, respectively, the CO2 loading of the lean phase solution and the rich phase solution are 0.33 mol / L and 2.77 mol / L, respectively, and the phase separation efficiency is 89.8%.

[0121] The mixed phase loading of absorbent #3 is 3.37 mol / L, the volumetric flow rate of the rich phase accounts for 30.6% of the total flow rate at the outlet of the phase separator, the volumetric flow rates of the lean phase solution and the rich phase solution are 0.25 L / min and 0.11 L / min, respectively, the CO2 loading of the lean phase solution and the rich phase solution are 0.37 mol / L and 4.66 mol / L, respectively, and the phase separation efficiency is 84.7%.

[0122] The mixed phase loading of absorbent #4 is 1.55 mol / L, the volumetric flow rate of the rich phase accounts for 65.8% of the total flow rate at the outlet of the phase separator, the volumetric flow rates of the lean phase solution and the rich phase solution are 0.13 L / min and 0.25 L / min, respectively, the CO2 loading of the lean phase solution and the rich phase solution are 0.46 mol / L and 2.24 mol / L, respectively, and the phase separation efficiency is 90.4%.

[0123] The mixed phase loading of absorbent #5 is 1.36 mol / L, the volumetric flow rate of the rich phase accounts for 69.0% of the total flow rate at the phase separator outlet, the volumetric flow rates of the lean phase solution and the rich phase solution are 0.09 L / min and 0.20 L / min, respectively, the CO2 loading of the lean phase solution and the rich phase solution are 0 mol / L and 2.1 mol / L, respectively, and the phase separation efficiency is 100%.

[0124] The phase separation efficiency is calculated using the following formula:

[0125]

[0126] In the above formula, η is the phase separation efficiency; C 富相 CO2 loading in the rich phase solution after phase separation, mol / L; C 贫相 V represents the CO2 loading in the lean phase solution after phase separation, in mol / L; 富相 V represents the flow rate of the rich phase solution after phase separation, in L / min; 贫相 The flow rate of the lean phase solution after phase separation is expressed in L / min.

[0127] Example 3

[0128] An energy and chemical company has its own coal-fired heating boiler with a designed flue gas flow rate of 12×10⁻⁶. 5 m 3 The carbon dioxide concentration is 12% per hour. The coal-fired flue gas first undergoes desulfurization, denitrification, and dust removal, achieving ultra-low emission levels for major pollutants. Then, the purified flue gas enters a pretreatment tower (alkali scrubbing tower) for further purification of sulfur dioxide and particulate matter concentrations, resulting in deeply purified flue gas.

[0129] The carbon capture process uses phase change absorbent #1 (30% TMBPA + 50% NHD + 20% H2O). The deeply purified flue gas is conveyed to the absorption tower, and the aforementioned phase change absorbent is introduced into the tower; the flow rate of the phase change absorbent is 480 m³ / h. 3 In the absorption tower, at a rate of / h, the phase change absorbent absorbs carbon dioxide from the flue gas and generates a mixed absorbent liquid; the mixed absorbent liquid is then processed by a coalescing device to obtain a coalescing product. The flow area of ​​the coalescing packing is 0.267 m². 2 The coalescing device is 10m long. Calculations show that the residence time of the mixed absorbent in the coalescing device is 30s, and the volume of the mixed absorbent is 4m³.3 .

[0130] Four parallel centrifugal phase separators are used to transport the coalescing products from the coalescing unit to the centrifugal phase separators, with each separator processing a flow rate of approximately 120 m³ / s. 3 / h. The temperature of the agglomerated product entering the centrifugal phase separator is 50°C; the agglomerated product is separated using the centrifugal phase separator to obtain a rich phase solution and a lean phase solution; the lean phase solution is conveyed to a mixing tank, and the rich phase solution is conveyed via a heat exchanger to a desorption tower for desorption treatment to obtain a regenerated absorbent; the flow rate of the lean phase solution conveyed to the mixing tank is approximately 280 m³ / h. 3 The flow rate of the rich phase solution delivered to the stripping column is approximately 200 m³ / h. 3 / h.

[0131] The regenerated absorbent is transported via the heat exchanger to the mixing tank and mixed with the lean phase solution to obtain a mixed absorbent, wherein the flow rate of the regenerated absorbent transported to the mixing tank is approximately 200 m³ / s. 3 The residence time of the regenerated absorbent in the mixing tank is 45 seconds, and the rotation speed of the stirring device in the mixing tank is 100 r / min. Finally, the mixed absorbent is conveyed to the absorption tower to absorb carbon dioxide in the next batch of flue gas. The flow rate of the mixed absorbent conveyed to the absorption tower is approximately 480 m³ / h. 3 / h.

[0132] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0133] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A dynamic amine-based carbon dioxide capture system, comprising: The system comprises a connected absorption tower, coalescing device, centrifugal phase separator, mixing tank and desorption tower, wherein, The absorption tower is internally connected to a phase change absorbent, and the mixed absorption liquid outlet of the absorption tower is connected to the mixed absorption liquid inlet of the coalescing device; The coalescing device is internally installed with coalescing packing, and the coalescing product outlet of the coalescing device is connected to the coalescing product inlet of the centrifugal phase separator, and the coalescing packing is derived from fiber material; the fiber material includes one or more than two combinations of stainless steel fiber, nylon fiber, polytetrafluoroethylene fiber and glass fiber; The lean phase solution outlet of the centrifugal phase separator is connected to the lean phase solution inlet of the mixing tank, and the rich phase solution outlet of the centrifugal phase separator is connected to the rich phase solution inlet of the desorption tower through a heat exchanger; The regeneration absorbent outlet of the desorption tower is connected to the regeneration absorbent inlet of the mixing tank through the heat exchanger; The mixing tank is used for mixing the regeneration absorbent and the lean phase solution in the mixing tank to obtain mixed absorbent, and the mixed absorbent outlet of the mixing tank is connected to the phase change absorbent inlet of the absorption tower.

2. The dynamic, split-phase carbon dioxide capture system of claim 1, wherein, An inter-stage cooling device is further arranged between the absorption tower packing layers in the absorption tower, which is used for cooling the gas generated in the process of absorbing carbon dioxide in the absorption tower; The top of the absorption tower is provided with an absorption tower demister.

3. The dynamic, phase-splitting carbon dioxide capture system of claim 1 or 2, wherein, The phase change absorbent includes a composite organic amine phase change absorbent.

4. The dynamic, split-phase carbon dioxide capture system of claim 3, wherein, The composite organic amine phase change absorbent includes organic amine, phase separation agent and water.

5. The dynamic, phase-splitting carbon dioxide capture system of claim 1 or 2, wherein, The coalescing device is externally provided with a coalescing device heat preservation layer.

6. The dynamic, split-phase carbon dioxide capture system of claim 1 or 2, wherein, The mixing tank is installed with a stirring device, and / or the mixing tank is further provided with a phase change absorbent supplement port.

7. The dynamic, phase-splitting carbon dioxide capture system of claim 1 or 2, wherein, The top of the desorption tower is provided with one or both of a desorption tower demister and a condenser; and / or the bottom of the desorption tower is provided with a reboiler.

8. The dynamic, split-phase carbon dioxide capture system of claim 7, wherein, The outer layer of the desorption tower is provided with a desorption tower heat preservation layer.

9. A method of carbon dioxide capture, characterized by, The system comprises the following steps: The flue gas is transported to the absorption tower, and the phase change absorbent is introduced into the absorption tower; in the absorption tower, the phase change absorbent absorbs carbon dioxide in the flue gas and generates mixed absorption liquid; The coalescing product obtained by processing the mixed absorption liquid through the coalescing device is transported to the centrifugal phase separator, and the coalescing product is separated by the centrifugal phase separator to obtain rich phase solution and lean phase solution; the coalescing device is internally installed with coalescing packing, and the coalescing packing is derived from fiber material; the fiber material includes one or more than two combinations of stainless steel fiber, nylon fiber, polytetrafluoroethylene fiber and glass fiber; The lean phase solution is transported to the mixing tank, and the rich phase solution is transported to the desorption tower through a heat exchanger for desorption treatment to obtain regeneration absorbent; The regeneration absorbent is transported to the mixing tank through the heat exchanger to mix with the lean phase solution to obtain mixed absorbent.

10. The carbon dioxide capture method of claim 9, wherein, The mixed absorbent is transported to the absorption tower for absorbing carbon dioxide in the flue gas.

11. The carbon dioxide capture method according to claim 9 or 10, characterized in that, The residence time of the mixed absorption liquid in the coalescing device is 10-120s; and / or, The temperature of the coalescing product entering the centrifugal phase separator is 40-60℃; and / or, The centrifugal phase separator rotates at a speed of 1000-8000 r / min; and / or, The flow rate of the rich phase solution delivered to the desorption column is 40-80% of the flow rate of the coalesced product, and the flow rate of the lean phase solution delivered to the mixing tank is 20-60% of the flow rate of the coalesced product.

12. The carbon dioxide capture method according to claim 9 or 10, characterized in that, The residence time of the lean phase solution and / or the regenerated absorbent in the mixing tank is 30-60 s; and / or, the stirring device of the mixing tank rotates at a speed of 30-200 r / min.

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