Method and system for reducing amine loss in absorption process of carbon capture process

Abstract

The present application belongs to the technical field of carbon capture, and particularly relates to a method and system for reducing amine loss in the absorption process of carbon capture technology. The method comprises: (1) under the conditions of the presence of a catalyst and bubbling, performing first contact between acid gas and aqueous washing solution to obtain acidified water washing water containing micron-sized bubbles; (2) performing second contact between decarburized amine-containing purified gas and the acidified water washing water, the acidified water washing water absorbing the amine in the amine-containing purified gas to obtain amine-removed purified gas and water washing solution; and (3) dividing the water washing solution into two streams, one of which is subjected to regeneration treatment to obtain amine and is recovered, and the other of which is returned to the aqueous washing solution. The micron-sized bubbles and acid in the acidified water washing water are used to capture the amine-containing aerosol in the gas in the absorption section of the carbon dioxide absorption tower, and the partial pressure of the amine in the gas is reduced, thereby greatly reducing the amine loss in the absorption process of the carbon capture technology.

Description

Technical Field

[0001] This invention belongs to the field of carbon capture technology, specifically relating to a method and system for reducing amine loss during the absorption process in carbon capture technology. Background Technology

[0002] Climate change caused by greenhouse gases has become a common challenge facing countries worldwide. Among all greenhouse gases, carbon dioxide emits the largest amount of carbon dioxide, making carbon reduction a hot research topic in addressing climate change. It is widely believed that carbon capture, utilization, and storage (CCUS) technology is one of the essential pathways to achieving carbon reduction.

[0003] Carbon dioxide capture is the first step in CCUS technology. Currently, the most mature carbon dioxide capture method is chemical absorption, which utilizes the acid-base reaction between alkanolamines and carbon dioxide. In the absorption tower, carbon dioxide from the feed gas is transferred to the alkanolamine absorbent. The absorbed carbon dioxide is then desorbed from the alkanolamine solvent through heating or vacuum, allowing for the recycling of the solvent. However, amine loss is a significant bottleneck in alkanolamine-based carbon dioxide capture technology. Due to the high vapor pressure of alkanolamine solvents, a large amount evaporates with the purified gas. Furthermore, during the absorption of carbon dioxide from the feed gas, gas-liquid contact leads to aerosol formation, trapping the amine solution within the aerosol and escaping the absorption tower with the gas – another major pathway for amine loss.

[0004] Currently, in industry, water washing is commonly used to wash the purified gas obtained after capturing carbon dioxide using the amine method. Through water washing, the partial pressure of amines in the gas phase is reduced, and the amine solution entrained in the gas phase can be washed off.

[0005] CN108404612 discloses a rich-liquid multi-stage heat exchange carbon dioxide capture system, comprising: an absorption tower containing an amine solution as an absorbent; the absorption tower being connected to a multi-stage liquid-liquid separation device via a rich-liquid pump, each stage of the liquid-liquid separation device forming a loop with the absorption tower; a water washing tower for absorbing and defoaming the purified flue gas discharged from the top of the water washing tower; a regeneration tower connected to the multi-stage liquid-liquid separation device via a heat exchanger, with a reboiler connected to the bottom of the regeneration tower, where the material expands to vaporize upon heating and returns to the regeneration tower; and a gas-liquid separator connected to the top of the regeneration tower via a heat exchanger, the gas-liquid separator forming a loop with the regeneration tower via a water cooler. In this system, amine loss is controlled using conventional water washing.

[0006] CN108568192 discloses an optimized carbon dioxide capture process, comprising: (1) flue gas, after being dehydrated and cooled by a fan, enters an absorption tower and flows from bottom to top. An amine solution is supplied from the top of the absorption tower as the absorbent, and the absorbent comes into countercurrent contact with the flue gas to remove carbon dioxide; the purified decarbonized flue gas enters a water scrubbing tower; (2) the rich liquid absorbed at the bottom of the absorption tower is pumped to a heat exchanger, and the rich liquid after heat exchange enters from the top of the regeneration tower, is stripped and desorbed, and then sent to a reboiler for reboiling; (3) the gas mixture discharged from the top of the regeneration tower is introduced into a heat exchanger for water cooling, and then enters a gas-liquid separator for gas-liquid separation, and the separated liquid is introduced into a water scrubbing tower. In this process, the control of amine loss also relies on conventional water scrubbing.

[0007] However, in existing water washing processes, as the concentration of amines in the wash water gradually increases, the partial pressure of amines in the gas phase after equilibrium also gradually increases, leading to a significant reduction in the washing effect. Simultaneously, with the application of various high-efficiency absorption devices, the generated aerosol particles are becoming increasingly smaller, while existing water washing processes have very limited effectiveness in recovering micron-sized aerosol particles. For these reasons, existing water washing processes are not ideal for amine recovery and cannot meet the needs of industrial economic operation.

[0008] Therefore, it is urgent to develop a new method to reduce amine loss during the absorption process of carbon capture technology. This is of great significance for improving the operating efficiency and economy of carbon capture technology. Summary of the Invention

[0009] The purpose of this invention is to address the problem that the traditional water washing method used in the absorption process of existing carbon capture processes to reduce amine loss has unsatisfactory amine recovery effect and cannot effectively recover amines in the form of aerosols entrained in the decarbonized gas, resulting in high amine loss. This invention provides a method and system for reducing amine loss in the absorption process of carbon capture processes.

[0010] To achieve the above objectives, a first aspect of the present invention provides a method for reducing amine loss during the absorption process in a carbon capture process, comprising:

[0011] (1) In the presence of a catalyst and under bubbling conditions, acidic gas and water-containing washing liquid are brought into first contact to obtain acidified water washing water containing micron-sized bubbles;

[0012] (2) The decarbonized amine-containing purified gas is brought into a second contact with the acidified washing water, and the acidified washing water absorbs the amine in the amine-containing purified gas to obtain deamine-reduced purified gas and washing liquid.

[0013] (3) The washing liquid is divided into two streams. One stream is regenerated to obtain amine and is recovered. The other stream is returned to the water-containing washing liquid.

[0014] A second aspect of the present invention provides a system for reducing amine loss during the absorption process in a carbon capture process. The system comprises: a gas-phase circulating fan, an acidification reactor, a gas-liquid separator, a water washing cooler, a water washing section of an absorption tower, a water washing liquid storage tank, a regenerator, and a water washing liquid pump; wherein,

[0015] The gas-phase circulating fan is used to transport acidic gas to the acidification reactor;

[0016] The acidification reactor is used to bring acidic gas and water-containing washing liquid into first contact in the presence of a catalyst and under bubbling conditions to obtain acidified water washing water containing micron-sized bubbles.

[0017] The gas-liquid separator is used to separate undissolved acidic gases from the acidified wash water and circulate them to the acidification reactor by the gas phase circulating fan, and to transport the acidified wash water to the wash water cooler for cooling.

[0018] The water washing section of the absorption tower is used to bring the amine-containing purified gas after decarbonization from the carbon dioxide absorption tower absorption section into a second contact with the cooled acidified water washing water. The acidified water washing water absorbs the amine in the amine-containing purified gas to obtain deamine-reduced purified gas and water washing liquid.

[0019] The washing liquid storage tank is used to store the washing liquid and divide the washing liquid into two streams. One stream is sent to the regenerator for regeneration treatment to obtain amine and recover it. The other stream is sent by the washing liquid pump to the acidification reactor and added to the water-containing washing liquid.

[0020] Through the above technical solution, the present invention has the following beneficial effects:

[0021] (1) The acidified wash water obtained after acidification treatment can react with amines in the gas phase to form salts, thereby reducing the volatilization loss of amines;

[0022] (2) The acidified washing water obtained after acidification treatment contains a large number of micron-sized bubbles, which can effectively aggregate with aerosols in the gas phase and dissolve them in the acidified washing water, thereby significantly reducing the entrainment loss of amines.

[0023] (3) The process is simple, does not require the introduction of other substances, and will not affect the purification performance of the carbon capture system. Attached Figure Description

[0024] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0025] Figure 1 This is a schematic diagram of the system provided by the present invention for reducing amine loss during the absorption process in carbon capture.

[0026] Explanation of reference numerals in the attached figures

[0027] 1-Gas phase circulating fan 2-Acidification reactor

[0028] 3-Gas-liquid separator 4-Water washing cooler

[0029] 5 - Absorber washing section; 6 - Washing liquid storage tank

[0030] 7-Regenerator 8-Washing liquid pump Detailed Implementation

[0031] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0032] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0033] The first aspect of this invention provides a method for reducing amine loss during the absorption process in a carbon capture process, comprising:

[0034] (1) In the presence of a catalyst and under bubbling conditions, acidic gas and water-containing washing liquid are brought into first contact to obtain acidified water washing water containing micron-sized bubbles;

[0035] (2) The decarbonized amine-containing purified gas is brought into a second contact with the acidified washing water, and the acidified washing water absorbs the amine in the amine-containing purified gas to obtain deamine-reduced purified gas and washing liquid.

[0036] (3) The washing liquid is divided into two streams. One stream is regenerated to obtain amine and is recovered. The other stream is returned to the water-containing washing liquid.

[0037] The method provided by this invention, based on the traditional water washing process, obtains acidified water washing water containing micron-sized bubbles by subjecting the water washing water to specific acidification treatment. The micron-sized bubbles and acid in the acidified water washing water are used to capture amine-containing aerosols in the gas exiting the absorption section of the carbon dioxide absorption tower, while reducing the partial pressure of amines in the gas, thereby significantly reducing amine loss in the absorption process of carbon capture.

[0038] According to the present invention, in step (1), the acidic gas can provide CO2 to hydrate with water to generate carbonic acid (H2CO3) and obtain weakly acidic acidified washing water; at the same time, the acidic gas enters the water-containing washing liquid as a gas stream to promote the generation of micron-sized bubbles.

[0039] In this invention, preferably, the acidic gas can be carbon dioxide and / or the carbon dioxide-containing feed gas in the carbon capture process. When the acidic gas is carbon dioxide, from the perspective of improving the material recycling efficiency in the carbon capture system, it is preferable to use the carbon dioxide product gas regenerated in the regeneration section.

[0040] According to the present invention, in step (1), the aqueous washing solution can be fresh water or process makeup water, or it can be the washing solution obtained from subsequent washing steps. In a preferred embodiment of the present invention, from the perspective of improving water utilization efficiency, fresh water is used in the initial stage of process operation. As the process continues to run, the proportion of the washing solution obtained from subsequent washing steps in the aqueous washing solution gradually increases, supplemented by fresh water.

[0041] According to the present invention, in step (1), the catalyst is an immobilized carbonic anhydrase, which can promote the hydration of carbon dioxide and water, which is beneficial to obtaining weakly acidic acidified wash water, and at the same time allows more carbon dioxide to dissolve in water, promoting the generation of micron-sized bubbles.

[0042] In this invention, the catalyst immobilized carbonic anhydrase is a conventional biochemical reagent. This invention does not have any particular limitations on it and it can be obtained through conventional commercial channels, such as from SIGMA Corporation (USA), Shanghai Aladdin Biochemical Technology Co., Ltd., Shanghai Yuanye Biotechnology Co., Ltd., Shanghai Huzheng Biotechnology Co., Ltd., Shanghai Yanqi Biotechnology Co., Ltd., etc.

[0043] Preferably, the mass ratio of the catalyst to the aqueous washing solution can be (0.1-3):100.

[0044] According to the present invention, in step (1), the first contact process includes: placing the catalyst in the aqueous washing liquid, and then introducing the acidic gas under bubbling conditions to carry out an acidification reaction, thereby obtaining acidified water washing water containing micron-sized bubbles. The bubbling conditions are preferably achieved by using a jet flow to introduce the acidic gas into the aqueous washing liquid at high speed, thereby further enhancing the gas-liquid contact area and better dispersing the acidic gas into the liquid phase in the form of micron-sized bubbles.

[0045] According to the present invention, in step (1), preferably, the conditions for the first contact include: the volume ratio of the acidic gas to the water-containing washing liquid is (1-100):1, more preferably (10-50):1; the temperature is 20-60℃, more preferably 30-50℃; and the time is 0.01-1h, more preferably 0.1-0.5h.

[0046] According to the present invention, in step (1), preferably, the pH value of the acidified washing water is 5-6.5; the diameter of the micron-sized bubbles in the acidified washing water is ≤500μm, more preferably ≤100μm, so as to obtain better amine recovery effect.

[0047] In this invention, there are no particular limitations on the method of obtaining the acidic gas jet. For example, a conventional commercially available nozzle can be used, and the size of the formed micron-sized bubbles can be controlled by selecting the nozzle orifice diameter and the gas jet velocity. This invention does not particularly limit the specifications of the nozzle or the parameters used to jet the acidic gas through the nozzle, as long as it can achieve the micron-sized bubbles within the diameter range described above in this invention.

[0048] According to the present invention, in step (2), the amine-containing purified gas after decarbonization refers to the gaseous product exiting the absorption section of the carbon dioxide absorption tower in the carbon capture process. Its carbon dioxide content already meets the decarbonization index requirements, but due to the volatilization of the amine solvent and the generation of aerosols from gas-liquid contact during the absorption of carbon dioxide from the raw gas in the absorption section, the gaseous product contains a certain amount of amine, existing in the form of gaseous amine and amine-containing aerosols. Preferably, the amine content in the amine-containing purified gas is 10-5000 ppm by mass.

[0049] In this invention, preferably, the amine in the amine-containing purified gas is at least one of monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), diisopropanolamine (DIPA), and N-methyldiethanolamine (MDEA).

[0050] According to the present invention, in step (2), the decarbonized amine-containing purified gas is brought into a second contact with acidified washing water, i.e., the amine-containing purified gas is washed with the acidified washing water to absorb the amine. During this process, micron-sized bubbles in the acidified washing water aggregate with amine-containing aerosols in the amine-containing purified gas, causing the latter to dissolve into the acidified washing water, thereby reducing the amine present in the gas phase in aerosol form. At the same time, the acid in the acidified washing water reacts with the amine in the gas phase to reduce the partial pressure of the amine in the gas phase, thereby significantly reducing the amine loss during the absorption process. In the present invention, the second contact is preferably a countercurrent contact. Preferably, the conditions for the second contact include: the volume ratio of the amine-containing purified gas to the acidified washing water is (10-500):1, preferably (250-450):1; and the temperature is 30-60°C.

[0051] According to the present invention, in step (2), the content of amine in the deamine purified gas is ≤30 ppm by mass, and it can be used as product gas collection or enter the subsequent process section for use.

[0052] According to the present invention, in step (3), the washing solution obtained after water washing can be regenerated to recover amine. The conditions for the regeneration treatment include: a temperature of 100-120°C and a pressure of atmospheric pressure. In addition, the washing solution can also be recycled back to the aqueous washing solution added in step (1). It should be noted that as the washing water is continuously recycled, it becomes a salt solution, and the decrease in its pH value before and after the first contact gradually decreases until it reaches equilibrium with carbon dioxide and cannot be further acidified. At this point, CO2 needs to be regenerated through thermal regeneration.

[0053] A second aspect of the present invention provides a system for reducing amine loss during the absorption process in carbon capture processes, such as... Figure 1 As shown, the system includes: a gas-phase circulating fan 1, an acidification reactor 2, a gas-liquid separator 3, a washing water cooler 4, a washing section of an absorption tower 5, a washing liquid storage tank 6, a regenerator 7, and a washing liquid pump 8; wherein,

[0054] The gas-phase circulating fan 1 is used to transport acidic gas to the acidification reactor 2;

[0055] The acidification reactor 2 is used to bring acidic gas and water-containing washing liquid into first contact in the presence of a catalyst and under bubbling conditions to obtain acidified water washing water containing micron-sized bubbles.

[0056] The gas-liquid separator 3 is used to separate the undissolved acidic gas in the acidified washing water and circulate it to the acidification reactor 2 by the gas phase circulating fan 1, and to transport the acidified washing water to the washing water cooler 4 for cooling.

[0057] The water washing section 5 of the absorption tower is used to bring the amine-containing purified gas after decarbonization from the carbon dioxide absorption tower absorption section into a second contact with the cooled acidified water washing water. The acidified water washing water absorbs the amine in the amine-containing purified gas to obtain deamine-reduced purified gas and water washing liquid.

[0058] The washing liquid storage tank 6 is used to store the washing liquid and divide the washing liquid into two streams. One stream is sent to the regenerator 7 for regeneration treatment to obtain amine and recover it. The other stream is sent by the washing liquid pump 8 to the acidification reactor 2 and added to the water-containing washing liquid.

[0059] According to the present invention, such as Figure 1 As shown, acidic gas (e.g., carbon dioxide-containing feed gas in a carbon capture process or carbon dioxide product gas regenerated from an off-site regeneration section) is transported to the acidification reactor 2 by the gas-phase circulating fan 1. Under the presence of a catalyst and bubbling conditions, it undergoes a first contact with the water-containing washing liquid and simultaneously undergoes an acidification reaction, yielding acidified wash water containing micron-sized bubbles. This acidified wash water containing micron-sized bubbles enters the gas-liquid separator 3 for gas-liquid separation, separating out undissolved acidic gas, which is then circulated back to the acidification reactor 2 by the gas-phase circulating fan 1 to continue participating in the first contact. The acidified wash water with undissolved gas then enters the wash water cooler 4 for cooling to meet the required temperature. The washing process requires that the cooled acidified wash water enters from the top of the washing section 5 of the absorption tower, while the amine-containing purified gas after decarbonization from the carbon dioxide absorption tower enters from the bottom of the washing section 5. The two undergo a second contact, where the acidified wash water absorbs the amine in the amine-containing purified gas. The resulting deamine-treated purified gas exits from the top of the washing section 5, and the resulting washing liquid exits from the bottom of the washing section 5 and enters the washing liquid storage tank 6. The washing liquid stored in the washing liquid storage tank 6 is divided into two streams: one stream enters the regenerator 7 for regeneration to obtain and recover the amine; the other stream is pumped back to the acidification reactor 2 by the washing liquid pump 8 and added to the aqueous washing liquid. Furthermore, as the washing water is continuously recycled, fresh water is added to the washing liquid storage tank 6 during its regeneration to maintain the quality and quantity of the washing water to meet process requirements.

[0060] The present invention will be described in detail below through embodiments. In the following embodiments and comparative examples,

[0061] The solid catalyst was an immobilized CA enzyme, purchased from SIGMA.

[0062] Unless otherwise specified, all other materials used are standard industrial-grade products.

[0063] Example 1

[0064] like Figure 1 As shown, the carbon dioxide product gas regenerated in the carbon capture process is transported to the acidification reactor 2 (filled with a solid catalyst) by a gas phase circulation fan 1, and then introduced into water (the mass ratio of solid catalyst to water is 1:100) in a jet stream for the first contact and simultaneously undergoes an acidification reaction (the volume ratio of carbon dioxide product gas to water is 30:1, the reaction temperature is 40℃, and the reaction time is 0.25h), resulting in acidified wash water containing micron-sized bubbles (pH value is 5.7, and the diameter of the micron-sized bubbles is <100μm). The acidified wash water enters the gas-liquid separator 3, where the undissolved acidic gas is separated and circulated back to the acidification reactor 2 by the gas phase circulation fan 1 to continue participating in the first contact. After that, the acidified wash water is transported to the wash water cooler 4 for cooling.

[0065] The cooled acidified washing water enters from the top of the washing section 5 of the carbon dioxide absorption tower, while the decarbonized amine-containing purified gas (amine content of 3100 ppm by mass) exiting the absorption section of the carbon dioxide absorption tower (using MEA solution as the absorbent) enters from the bottom of the washing section 5. The two are in countercurrent contact, and the acidified washing water absorbs the amine in the amine-containing purified gas (the volume ratio of amine-containing purified gas to acidified washing water is 300:1, and the temperature is 40℃). The resulting deamine-removed purified gas is discharged from the top of the washing section 5, and the resulting washing liquid is discharged from the bottom of the washing section 5 and enters the washing liquid storage tank 6.

[0066] The washing liquid stored in the washing liquid storage tank 6 is divided into two streams. One stream enters the regenerator 7 for regeneration treatment (regeneration temperature is 105℃, pressure is atmospheric pressure) to obtain amine and recover it. The other stream is sent back to the acidification reactor 2 by the washing liquid pump 8 and added to the water to continue participating in the first contact. When the pH value of the circulating washing water entering and leaving the acidification reactor 2 remains basically unchanged, it indicates that it can no longer be acidified and needs to be sent to the regeneration tower for regeneration. At the same time, fresh water is added to the washing liquid storage tank 6 to maintain the quality and quantity of the washing water to meet the process requirements.

[0067] The test results showed that the amine content in the purified gas was 11 ppm by mass.

[0068] Comparative Example 1

[0069] Using a conventional water washing method (not using the acidified water containing micron-sized bubbles as in Example 1), fresh water was used as the washing water to wash the decarbonized amine-containing purified gas (composition as in Example 1) (the volume ratio of amine-containing purified gas to washing water and the washing temperature and other conditions were the same as in Example 1).

[0070] The test results showed that the amine content in the purified gas was 540 ppm by mass.

[0071] Example 2

[0072] like Figure 1 As shown, the carbon dioxide product gas regenerated in the carbon capture process is transported to the acidification reactor 2 (filled with a solid catalyst) by a gas phase circulation fan 1, and then introduced into water (the mass ratio of solid catalyst to water is 1:100) in a jet stream for the first contact and simultaneously undergoes an acidification reaction (the volume ratio of carbon dioxide product gas to water is 25:1, the reaction temperature is 45℃, and the reaction time is 0.3h), resulting in acidified wash water containing micron-sized bubbles (pH value is 5.8, and the diameter of the micron-sized bubbles is <80μm). The acidified wash water enters the gas-liquid separator 3, where the undissolved acidic gas is separated and circulated back to the acidification reactor 2 by the gas phase circulation fan 1 to continue participating in the first contact. After that, the acidified wash water is transported to the wash water cooler 4 for cooling.

[0073] The cooled acidified wash water enters from the top of the water washing section 5 of the carbon dioxide absorption tower, while the decarbonized amine-containing purified gas (amine content of 2900 ppm by mass) exiting the absorption section of the carbon dioxide absorption tower (using a compound solution of MEA and MDEA as absorbent) enters from the bottom of the water washing section 5. The two are in countercurrent contact, and the acidified wash water absorbs the amine in the amine-containing purified gas (the volume ratio of amine-containing purified gas to acidified wash water is 350:1, and the temperature is 42℃). The resulting deamine-removed purified gas is discharged from the top of the water washing section 5, and the resulting wash liquid is discharged from the bottom of the water washing section 5 and enters the wash liquid storage tank 6.

[0074] The washing liquid stored in the washing liquid storage tank 6 is divided into two streams. One stream enters the regenerator 7 for regeneration treatment (temperature 106℃, pressure atmospheric pressure) to obtain amine and recover it. The other stream is pumped back to the acidification reactor 2 by the washing liquid pump 8 and added to the water to continue participating in the first contact. When the pH value of the circulating washing water entering and leaving the acidification reactor 2 remains basically unchanged, it indicates that it can no longer be acidified and needs to be sent to the regeneration tower for regeneration. At the same time, fresh water is added to the washing liquid storage tank 6 to maintain the quality and quantity of the washing water to meet the process requirements.

[0075] The amine content in the purified gas obtained after deamine removal was tested to be 16 ppm by mass.

[0076] Comparative Example 2

[0077] Using a conventional water washing method (not using the acidified water containing micron-sized bubbles as in Example 2), fresh water was used as the washing water to wash the decarbonized amine-containing purified gas (composition as in Example 2) (the volume ratio of amine-containing purified gas to washing water and the washing temperature and other conditions were the same as in Example 2).

[0078] The test results showed that the amine content in the purified gas was 480 ppm by mass.

[0079] Example 3

[0080] like Figure 1 As shown, the carbon dioxide product gas regenerated in the carbon capture process is transported to the acidification reactor 2 (filled with a solid catalyst) by a gas phase circulation fan 1, and then introduced into water (the mass ratio of solid catalyst to water is 1:100) in a jet stream for the first contact and simultaneously undergoes an acidification reaction (the volume ratio of carbon dioxide product gas to water is 15:1, the reaction temperature is 50℃, and the reaction time is 0.4h), resulting in acidified wash water containing micron-sized bubbles (pH value is 5.6, and the diameter of the micron-sized bubbles is <90μm). The acidified wash water enters the gas-liquid separator 3, where the undissolved acidic gas is separated and circulated back to the acidification reactor 2 by the gas phase circulation fan 1 to continue participating in the first contact. After that, the acidified wash water is transported to the wash water cooler 4 for cooling.

[0081] The cooled acidified wash water enters from the top of the washing section 5 of the carbon dioxide absorption tower, while the decarbonized amine-containing purified gas (amine content of 3500 ppm by mass) exiting the absorption section of the carbon dioxide absorption tower (using MEA solution as the absorbent) enters from the bottom of the washing section 5. The two are in countercurrent contact, and the acidified wash water absorbs the amine in the amine-containing purified gas (the volume ratio of amine-containing purified gas to acidified wash water is 330:1, and the temperature is 45℃). The resulting deamine-removed purified gas is discharged from the top of the washing section 5, and the resulting washing liquid is discharged from the bottom of the washing section 5 and enters the washing liquid storage tank 6.

[0082] The washing liquid stored in the washing liquid storage tank 6 is divided into two streams. One stream enters the regenerator 7 for regeneration treatment (regeneration temperature is 105℃, pressure is atmospheric pressure) to obtain amine and recover it. The other stream is sent back to the acidification reactor 2 by the washing liquid pump 8 and added to the water to continue participating in the first contact. When the pH value of the circulating washing water entering and leaving the acidification reactor 2 remains basically unchanged, it indicates that it can no longer be acidified and needs to be sent to the regeneration tower for regeneration. At the same time, fresh water is added to the washing liquid storage tank 6 to maintain the quality and quantity of the washing water to meet the process requirements.

[0083] The amine content in the purified gas obtained after deamine removal was tested to be 14 ppm by mass.

[0084] Comparative Example 3

[0085] Using a conventional water washing method (not using the acidified water containing micron-sized bubbles as in Example 3), fresh water was used as the washing water to wash the decarbonized amine-containing purified gas (composition as in Example 3) (the volume ratio of amine-containing purified gas to washing water and the washing temperature and other conditions were the same as in Example 3).

[0086] The amine content in the purified gas obtained after deamine removal was tested to be 390 ppm by mass.

[0087] Example 4

[0088] like Figure 1 As shown, the carbon dioxide product gas regenerated in the carbon capture process is transported to the acidification reactor 2 (filled with a solid catalyst) by a gas phase circulation fan 1, and then introduced into water (the mass ratio of solid catalyst to water is 1:100) in a jet stream for the first contact and simultaneously undergoes an acidification reaction (the volume ratio of carbon dioxide product gas to water is 5:1, the reaction temperature is 25℃, and the reaction time is 0.05h), resulting in acidified wash water containing micron-sized bubbles (pH value is 6.2, and the diameter of the micron-sized bubbles is <500μm). The acidified wash water enters the gas-liquid separator 3, where the undissolved acidic gas is separated and circulated back to the acidification reactor 2 by the gas phase circulation fan 1 to continue participating in the first contact. After that, the acidified wash water is transported to the wash water cooler 4 for cooling.

[0089] The cooled acidified wash water enters from the top of the water washing section 5 of the carbon dioxide absorption tower, while the decarbonized amine-containing purified gas (amine content of 2400 ppm by mass) exiting the absorption section of the carbon dioxide absorption tower (using a compound solution of MEA and TEA as absorbent) enters from the bottom of the water washing section 5. The two are in countercurrent contact, and the acidified wash water absorbs the amine in the amine-containing purified gas (the volume ratio of amine-containing purified gas to acidified wash water is 100:1, and the temperature is 40℃). The resulting deamine-removed purified gas is discharged from the top of the water washing section 5, and the resulting wash liquid is discharged from the bottom of the water washing section 5 and enters the wash liquid storage tank 6.

[0090] The washing liquid stored in the washing liquid storage tank 6 is divided into two streams. One stream enters the regenerator 7 for regeneration treatment (temperature 105℃, pressure atmospheric pressure) to obtain amine and recover it. The other stream is pumped back to the acidification reactor 2 by the washing liquid pump 8 and added to the water to continue participating in the first contact. When the pH value of the circulating washing water entering and leaving the acidification reactor 2 remains basically unchanged, it indicates that it can no longer be acidified and needs to be sent to the regeneration tower for regeneration. At the same time, fresh water is added to the washing liquid storage tank 6 to maintain the quality and quantity of the washing water to meet the process requirements.

[0091] The test results showed that the amine content in the purified gas was 27 ppm by mass.

[0092] Comparative Example 4

[0093] Using a conventional water washing method (not using the acidified water containing micron-sized bubbles as in Example 4), fresh water was used as the washing water to wash the decarbonized amine-containing purified gas (composition as in Example 4) (the volume ratio of amine-containing purified gas to washing water and the washing temperature and other conditions were the same as in Example 4).

[0094] The test results showed that the amine content in the purified gas was 510 ppm by mass.

[0095] Example 5

[0096] like Figure 1 As shown, the carbon dioxide product gas regenerated in the carbon capture process is transported to the acidification reactor 2 (filled with a solid catalyst) by a gas phase circulation fan 1, and then introduced into water (the mass ratio of solid catalyst to water is 1:100) in a jet stream for the first contact and simultaneously undergoes an acidification reaction (the volume ratio of carbon dioxide product gas to water is 3:1, the reaction temperature is 55℃, and the reaction time is 0.2h), resulting in acidified wash water containing micron-sized bubbles (pH value is 5.9, and the diameter of the micron-sized bubbles is <300μm). The acidified wash water enters the gas-liquid separator 3, where the undissolved acidic gas is separated and circulated back to the acidification reactor 2 by the gas phase circulation fan 1 to continue participating in the first contact. After that, the acidified wash water is transported to the wash water cooler 4 for cooling.

[0097] The cooled acidified washing water enters from the top of the washing section 5 of the carbon dioxide absorption tower, while the decarbonized amine-containing purified gas (amine content of 2870 ppm by mass) exiting the absorption section of the carbon dioxide absorption tower (using MEA solution as the absorbent) enters from the bottom of the washing section 5. The two are in countercurrent contact, and the acidified washing water absorbs the amine in the amine-containing purified gas (the volume ratio of amine-containing purified gas to acidified washing water is 500:1, and the temperature is 45℃). The resulting deamine-removed purified gas is discharged from the top of the washing section 5, and the resulting washing liquid is discharged from the bottom of the washing section 5 and enters the washing liquid storage tank 6.

[0098] The washing liquid stored in the washing liquid storage tank 6 is divided into two streams. One stream enters the regenerator 7 for regeneration treatment (temperature 104℃, pressure atmospheric pressure) to obtain amine and recover it. The other stream is pumped back to the acidification reactor 2 by the washing liquid pump 8 and added to the water to continue participating in the first contact. When the pH value of the circulating washing water entering and leaving the acidification reactor 2 remains basically unchanged, it indicates that it can no longer be acidified and needs to be sent to the regeneration tower for regeneration. At the same time, fresh water is added to the washing liquid storage tank 6 to maintain the quality and quantity of the washing water to meet the process requirements.

[0099] The amine content in the purified gas obtained after deamine removal was tested to be 29 ppm by mass.

[0100] Comparative Example 5

[0101] Using a conventional water washing method (not using the acidified water containing micron-sized bubbles as in Example 5), fresh water was used as the washing water to wash the decarbonized amine-containing purified gas (composition as in Example 5) (the volume ratio of amine-containing purified gas to washing water and the washing temperature and other conditions were the same as in Example 5).

[0102] The test results showed that the amine content in the purified gas was 680 ppm by mass.

[0103] Example 6

[0104] like Figure 1 As shown, the carbon dioxide product gas regenerated in the carbon capture process is transported to the acidification reactor 2 (filled with a solid catalyst) by a gas phase circulation fan 1, and then introduced into water (the mass ratio of solid catalyst to water is 1:100) in a jet stream for the first contact and simultaneously undergoes an acidification reaction (the volume ratio of carbon dioxide product gas to water is 30:1, the reaction temperature is 40℃, and the reaction time is 0.2h), resulting in acidified wash water containing micron-sized bubbles (pH value is 5.7, and the diameter of the micron-sized bubbles is <150μm). The acidified wash water enters the gas-liquid separator 3, where the undissolved acidic gas is separated and circulated back to the acidification reactor 2 by the gas phase circulation fan 1 to continue participating in the first contact. After that, the acidified wash water is transported to the wash water cooler 4 for cooling.

[0105] The cooled acidified wash water enters from the top of the water washing section 5 of the carbon dioxide absorption tower, while the decarbonized amine-containing purified gas (amine content of 3300 ppm by mass) exiting the absorption section of the carbon dioxide absorption tower (using a formula solution of MEA and DEA as absorbent) enters from the bottom of the water washing section 5. The two are in countercurrent contact, and the acidified wash water absorbs the amine in the amine-containing purified gas (the volume ratio of amine-containing purified gas to acidified wash water is 330:1, and the temperature is 35℃). The resulting deamine-removed purified gas is discharged from the top of the water washing section 5, and the resulting wash liquid is discharged from the bottom of the water washing section 5 and enters the wash liquid storage tank 6.

[0106] The washing liquid stored in the washing liquid storage tank 6 is divided into two streams. One stream enters the regenerator 7 for regeneration treatment (temperature 107℃, pressure atmospheric pressure) to obtain amine and recover it. The other stream is pumped back to the acidification reactor 2 by the washing liquid pump 8 and added to the water to continue participating in the first contact. When the pH value of the circulating washing water entering and leaving the acidification reactor 2 remains basically unchanged, it indicates that it can no longer be acidified and needs to be sent to the regeneration tower for regeneration. At the same time, fresh water is added to the washing liquid storage tank 6 to maintain the quality and quantity of the washing water to meet the process requirements.

[0107] The test results showed that the amine content in the purified gas was 25 ppm by mass.

[0108] Comparative Example 6

[0109] Using a conventional water washing method (not using the acidified water containing micron-sized bubbles as in Example 6), fresh water was used as the washing water to wash the decarbonized amine-containing purified gas (composition as in Example 6) (the volume ratio of amine-containing purified gas to washing water and the washing temperature and other conditions were the same as in Example 6).

[0110] The test results showed that the amine content in the purified gas was 790 ppm by mass.

[0111] By comparing the results of Examples 1-6 with those of Comparative Examples 1-6, it can be seen that, compared with the traditional water washing method, the amine content in the purified gas obtained by the method and system of the present invention is significantly reduced, which has the effect of significantly reducing amine loss in the absorption process of carbon capture.

[0112] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method of reducing amine loss in an absorption process in a carbon capture process, characterized by, The method comprises: (1) contacting an acidic gas and an aqueous washing solution in the presence of a catalyst and under bubbling conditions to obtain acidified water washing water containing micron-sized bubbles; (2) contacting decarbonated amine-containing purified gas with the acidified water washing water, the acidified water washing water absorbing the amine in the amine-containing purified gas to obtain deaminated purified gas and water washing solution; (3) dividing the water washing solution into two streams, one of which is subjected to regeneration treatment to obtain amine and is recycled, and the other of which is returned to the aqueous washing solution.

2. The method of claim 1, wherein, In step (1), the acidic gas is carbon dioxide and / or a carbon dioxide-containing raw material gas in a carbon capture process.

3. The method of claim 1 or 2, wherein, In step (1), the catalyst is immobilized carbonic anhydrase. And / or, the mass ratio of the catalyst to the aqueous washing solution is (0.1-3):

100.

4. The method of claim 1 or 2, wherein, In step (1), the first contacting conditions include that the volume ratio of the acidic gas to the washing solution is (1-100):1, the temperature is 20-60°C, and the time is 0.01-1h.

5. The method of claim 4, wherein, In step (1), the first contacting conditions include that the volume ratio of the acidic gas to the washing solution is (10-50):1, the temperature is 30-50°C, and the time is 0.1-0.5h.

6. The method of claim 1 or 2, wherein, In step (1), the pH value of the acidified water washing water is 5-6.

5. And / or, the diameter of the micron-sized bubbles in the acidified water washing water is ≤500μm.

7. The method of claim 6, wherein, In step (1), the diameter of the micron-sized bubbles in the acidified water washing water is ≤100μm.

8. The method of claim 1 or 2, wherein, In step (2), the amine in the amine-containing purified gas is at least one of monoethanolamine, diethanolamine, triethanolamine, diisopropanolamine and N-methyldiethanolamine. And / or, the content of the amine in the amine-containing purified gas is 10-5000 mass ppm.

9. The method of claim 1 or 2, wherein, In step (2), the second contacting conditions include that the volume ratio of the amine-containing purified gas to the acidified water washing water is (10-500):1, and the temperature is 30-60°C.

10. The method of claim 9, wherein, In step (2), the second contacting conditions include that the volume ratio of the amine-containing purified gas to the acidified water washing water is (250-450):

1.

11. The method of claim 1 or 2, wherein, In step (2), the content of the amine in the deaminated purified gas is ≤30 mass ppm.

12. The method of claim 1 or 2, wherein, In step (3), the regeneration treatment conditions include that the temperature is 100-120°C and the pressure is normal pressure.

13. A system for reducing amine loss in an absorption process in a carbon capture process, characterized in that, The system comprises a gas phase circulating fan (1), an acidification reactor (2), a gas-liquid separator (3), a water washing water cooler (4), a water washing section of an absorption tower (5), a water washing solution storage tank (6), a regenerator (7) and a water washing solution pump (8); wherein, The gas phase circulating fan (1) is used to deliver the acidic gas to the acidification reactor (2); The acidification reactor (2) is used to contact the acidic gas and the aqueous washing solution in the presence of a catalyst and under bubbling conditions to obtain acidified water washing water containing micron-sized bubbles; The gas-liquid separator (3) is used to separate the undissolved acidic gas in the acidified water washing water and deliver it to the acidification reactor (2) by the gas phase circulating fan (1), and deliver the acidified water washing water to the water washing water cooler (4) for cooling; The absorption tower water washing section (5) is used for the second contact of the decarburized amine-containing purified gas from the carbon dioxide absorption tower absorption section and the cooled acidified water washing water, the amine in the amine-containing purified gas is absorbed by the acidified water washing water, and the deaminated purified gas and the water washing liquid are obtained; The water washing liquid storage tank (6) is used for storing the water washing liquid, and the water washing liquid is divided into two streams, one of which is transported to the regenerator (7) for regeneration treatment, and the amine is obtained and recovered; the other is transported to the acidification reactor (2) by the water washing liquid pump (8) and added to the water-containing washing liquid.

Images