Electrolytic regeneration of CO2-rich alkaline absorbents for CO2 capture
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-03-03
- Publication Date
- 2026-03-10
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Abstract
Description
[Technical field]
[0001] The present invention relates to a process for scrubbing a gas, such as a flue gas, containing carbon dioxide, followed by electrolytic regeneration of the spent aqueous scrubbing solution. 2 ) and oxygen (O 2 ) to produce substantially pure gaseous carbon dioxide (CO 2 The substantially pure carbon dioxide is then converted into liquid CO for transport. 2 It is compressed to CO 2 may be extracted from flue gas, ambient air or other sources. [Background technology]
[0002] Carbon Dioxide (CO 2 Carbon dioxide (CO2) is a gas that, when emitted into the atmosphere, has a negative impact on the climate because it contributes to the greenhouse effect and the rise in global temperatures. Carbon dioxide is produced, for example, as a by-product when fossil fuels, such as coal, gasoline, or diesel fuel, are burned. Coal-fired and gas-fired power plants produce CO 2 Reducing carbon dioxide emissions is a goal for many sectors.
[0003] From combustion, CO 2 The exhaust gas containing CO typically means flue gas or exhaust gas. 2 By lowering the CO content, 2 Depleting the gas is called gas cleaning, i.e. 2 CO from the gas stream by absorbing / dissolving it in a liquid. 2 This can be done by removing
[0004] As described in US11219860, CO extracted from the scrubbing process or from the anode compartment of the electrolysis cell after regeneration of the scrubbing solution is 2The gaseous CO is then conventionally compressed or cooled and compressed for transport off-site for other downstream uses. 2 The process of cooling and compressing CO into liquid carbon dioxide requires significant amounts of electricity. 2 There is an urgent need for an improved cleaning system, preferably requiring less power for the capture and compression of the. The method according to the invention can be obtained using the method and system disclosed in US11219860.
[0005] The embodiments described in the present disclosure have been made with the above considerations in mind and others. It is an object of the present disclosure to provide improved methods for preparing substantially pure gaseous carbon dioxide, as well as systems and uses thereof.
[0006] The invention is defined by the accompanying independent claims. Embodiments are set out in the accompanying dependent claims and the following description.
[0007] Therefore, carbon dioxide (CO 2 ) and oxygen (O 2 A method is provided for preparing substantially pure gaseous carbon dioxide from a gaseous mixture of oxygen and carbon dioxide (CO), the gaseous mixture being withdrawn from an anode chamber of an electrolytic cell, the electrolytic cell being supplied with spent aqueous scrubbing solution from a scrubber, the scrubber scrubbing gas having a first carbon dioxide concentration with a first alkaline aqueous scrubbing solution, the spent aqueous scrubbing solution being regenerated in the electrolytic cell by electrolysis, the regeneration comprising the step of: 2 ), the gaseous mixture comprising 66-80% v / v carbon dioxide and 20% v / v-34% v / v oxygen, and the method further comprises generating a gaseous mixture of oxygen and carbon dioxide (CO 2 treating the gaseous mixture with water to remove at least 50% of the oxygen from the gaseous mixture.
[0008] An aqueous wash liquid may be circulated between the electrolytic cell and the scrubber, where the wash liquid may be a first alkaline, where a first spent aqueous wash liquid is fed to the electrolytic cell and a first regenerated aqueous wash liquid is fed from the electrolytic cell back to the scrubber after regeneration in the electrolytic cell. The treatment of the gaseous mixture of oxygen and carbon dioxide to remove oxygen from said gaseous mixture may be performed using a gas separation device, where the gas separation device may be an adsorbent / solvent gas separator, a membrane separator and / or a cryogenic distillation separator, or a CO 2 From Rich Style 2 Separating and reducing O 2 CO content 2 It may be any suitable method / apparatus for treating a stream to produce a rich stream.
[0009] Regeneration of the cleaning solution in the electrolytic cell results in the generation of a gaseous mixture of oxygen and carbon dioxide.
[0010] This means that at least a significant amount of oxygen is removed from the mixture. Removing oxygen, i.e., removing CO from the gaseous mixture from the anode compartment of the electrolysis cell. 2 From O 2 By separating CO 2 In the compression stage, an increase in efficiency is obtained. A decrease in efficiency correlates with a decrease in the volume of gas to be compressed, e.g., 80% v / v CO 2 in 20% v / v O 2 If present, energy consumption can be reduced to 80% of the original value.
[0011] The carbon capture reaction in the scrubbing step is carried out automatically. Thus, the operation of the scrubber is an automatic process and does not require any power other than that required to circulate the liquid. The regeneration process of the first scrubbing liquid, which takes place in the cathode and anode compartments of the electrolysis cell, is an electrochemical reaction, which essentially requires power. This electrochemical process regenerates the solvent and produces hydrogen at the cathode and carbon dioxide (CO 2 ) at the anode. 2Regeneration thus comprises generating, by electrolysis, gaseous hydrogen in the cathode chamber and a gaseous mixture of oxygen and carbon dioxide in the anode chamber.
[0012] According to the present disclosure, the percentage of concentration of a liquid or gas may be defined by % v / v, i.e., the volumetric concentration of the solution, where 80% CO 2 and 20% O 2 A solution with 100 units of solution will have 80 units of CO 2 and 20 units of O 2 where the units may be ml, liters.
[0013] According to a first embodiment, at least 60% of the oxygen is removed from the gaseous mixture, or at least 70% of the oxygen is removed from the gaseous mixture, or at least 80% of the oxygen is removed from the gaseous mixture, or at least 90% of the oxygen is removed from the gaseous mixture, or at least 95% of the oxygen is removed from the gaseous mixture, or at least 99% of the oxygen is removed from the gaseous mixture. This means that substantially all of the oxygen can be removed before compression, which further increases the energy saved during the compression stage.
[0014] According to a first aspect, the method may further comprise compressing the oxygen-depleted gaseous mixture into substantially pure liquid carbon dioxide, which means that the liquid carbon can be easily transported for other downstream uses. The gas having the first carbon dioxide concentration is one of flue gas, exhaust gas, or air.
[0015] According to one alternative of the first aspect, the step of treating the gaseous mixture to remove at least 50% of the oxygen from the gaseous mixture comprises flowing the gaseous mixture through a heating device, thereby consuming the oxygen and producing carbon dioxide and dihydrogen oxide (H 2The heating device may be a separate burner or may be a generator, for example, producing district heating and electricity, and the total flow of the gaseous mixture of carbon dioxide and oxygen may be used instead of air. Thus, the carbon dioxide and water may be further separated by condensation to produce pure CO 2 The may be further cleaned, cooled, and compressed for transportation.
[0016] The heating device may be supplied with a fuel, which may be one of hydrogen, natural gas, or biogas, and the hydrogen may be gaseous hydrogen withdrawn from the cathode chamber of the electrolysis cell.
[0017] According to another alternative of the first aspect, the step of treating the gaseous mixture to remove at least 50% of oxygen from the gaseous mixture comprises treating the gaseous mixture with CO 2 The process may comprise utilizing said gaseous mixture as an oxidant in a process step for scrubbing flue gas.
[0018] Throughout this process, the flue gas will intermittently contain pure CO when all of the oxidant is oxygen mixed with carbon dioxide. 2 and therefore pure CO 2 can be directly cooled and compressed for transport with limited pre-treatment.
[0019] According to yet another alternative of the first aspect, treating the gaseous mixture to remove at least 50% oxygen from the gaseous mixture comprises utilizing the gaseous mixture as an oxidant in an aerobic biological treatment process.
[0020] Aerobic biological treatment processes refer, for example, to wastewater purification processes, during which oxygen is depleted during the wastewater purification process and purified CO 2 can be collected, cooled, and compressed for transportation.
[0021] According to a second aspect, there is provided a system for scrubbing a gas, such as a flue gas or exhaust gas, comprising carbon dioxide, to deplete carbon dioxide from the flue gas, the system comprising: - a scrubber unit for scrubbing the gas with an alkaline aqueous scrubbing liquid, comprising a scrubber; a regeneration device for regenerating the used aqueous cleaning liquid by electrolysis, wherein - the regeneration apparatus comprises an electrolysis cell comprising an anode chamber having an anode inlet for receiving the spent aqueous cleaning solution and an anode outlet for drawing oxygen and carbon dioxide; wherein the scrubber is in flow communication with the electrolytic cell; a gas separation device for separating the oxygen and carbon dioxide withdrawn from the anode chamber from each other; - a compressor unit for compressing the substantially pure carbon dioxide withdrawn from the separation device.
[0022] According to a third aspect there is provided a regeneration apparatus for regenerating used aqueous cleaning liquid to provide an alkaline aqueous cleaning liquid, the regeneration apparatus comprising an electrolysis cell comprising an anode chamber having an anode inlet for receiving the used aqueous cleaning liquid and an anode outlet for withdrawing oxygen and carbon dioxide, wherein the cathode chamber has an outlet for withdrawing the regenerated aqueous cleaning liquid; - a gas separation device for separating oxygen and carbon dioxide from each other from the anode chamber; - a compressor unit for compressing the carbon dioxide withdrawn from the first gas separation device; Equipped with.
[0023] According to one alternative of the system according to the second or third aspect, the gas separation device may be a heating device, by which is meant a device such as a burner, an engine or a generator.
[0024] According to another alternative, the gas separation device may be an aerobic biological process facility, such as a wastewater treatment plant.
[0025] According to the second and third aspects, at least 50% of the oxygen is removed from the gaseous mixture of carbon dioxide and oxygen withdrawn from the anode chamber by or in the gas separation device. Alternatively, at least 60% of the oxygen is removed from the gaseous mixture, or at least 70% of the oxygen is removed from the gaseous mixture, or at least 80% of the oxygen is removed from the gaseous mixture, or at least 90% of the oxygen is removed from the gaseous mixture, or at least 95% of the oxygen is removed from the gaseous mixture, or at least 99% of the oxygen is removed from the gaseous mixture.
[0026] Although the present invention has been described above with reference to specific embodiments, it is not intended that the present invention be limited to the specific form set forth herein. Rather, the present invention is limited only by the appended claims, and other embodiments than the specific embodiments described above are equally possible within the scope of these appended claims.
[0027] In the claims, the term "comprises / comprising" does not exclude the presence of other elements or steps. Additionally, although individual features may be included in different claims, these features may in some cases be advantageously combined, and the inclusion in different claims does not imply that a combination of these features is not feasible and / or advantageous.
[0028] In addition, singular references do not exclude a plurality. Terms such as "a," "an," "first," "second," etc. do not exclude a plurality.
[0029] These and other aspects, features and advantages of the present invention will become apparent and elucidated from the following description of embodiments of the invention, which proceeds with reference to the accompanying drawings. [Brief description of the drawings]
[0030] [Figure 1]FIG. 1 shows the flow path between the scrubber and the electrolytic cell. [Diagram 2] FIG. 2 shows the regeneration apparatus of the process scheme. [Diagram 3] FIG. 3 shows the voltage / current graph of the electrolytic cell. [Figure 4] FIG. 4 shows a graph illustrating the CO2 concentration in volume percentage of the CO2 mixed stream exiting the electrolysis cell. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] Referring to FIG. 1, a system 100 according to one embodiment is shown having a scrubber unit 200 and a regeneration unit 300. Here, carbon dioxide CO 2 Schematically shown is a method for scrubbing a gas, such as a flue gas or exhaust gas, comprising: a scrubber unit 200 and a regenerator unit 300 which may be operated independently.
[0032] The gases scrubbed in the scrubber can be, for example, flue gas or exhaust gas. One alternative is to utilize a scrubber and regeneration on the vehicle. Another option is to extract CO from ambient air. 2 Capture and concentrate CO 2 This may be a so-called DAC (Direct Air Capture) application, in which a flow of air is generated.
[0033] Gas enters the scrubber through the scrubber inlet 213. Carbon dioxide CO 2 To dramatically reduce CO2 emissions, the scrubbing method can be described as follows: The gas is scrubbed in a scrubber 210 in a countercurrent manner with a first alkaline aqueous scrubbing liquid to remove carbon dioxide CO2. 2 , bicarbonate HCO 3 - and / or carbonate CO 3 2- Dissolve in the first alkaline aqueous wash as dissolved bicarbonate HCO 3 - and / or carbonate CO 3 2-The result is a first spent aqueous cleaning solution comprising: The first used aqueous cleaning liquid has a pH of about 7 to about 11, or usually about 7 to about 9, when it leaves the outlet 211″ for withdrawing the used aqueous cleaning liquid of the scrubber 210. The first used aqueous cleaning liquid is then fed to the anode chamber 313 of the electrolysis cell 310 via the anode inlet 313′. In addition to the anode chamber 313, the electrolysis cell 310 also has a cathode chamber 312. The anode chamber 313 and the cathode chamber 312 are separated by a membrane 311. This membrane 311 may be a semi-permeable membrane, being permeable to cations but essentially impermeable to anions. Thus, the membrane is a cation exchange membrane. Electrolysis increases the pH of the first used aqueous cleaning liquid in the cathode chamber 312. In the anode chamber 313, electrolysis reduces the pH value and releases gaseous carbon dioxide, thereby removing bicarbonate HCO from the first used aqueous cleaning liquid. 3 - and carbonate CO 3 2- The outlet 211" for used aqueous cleaning liquid of the scrubber 210 is in flow communication with an inlet 313' for used aqueous cleaning liquid of the anode chamber 313. Furthermore, the outlet 312" for regenerated aqueous cleaning liquid of the cathode chamber 312 is in flow communication with an inlet 212' for alkaline aqueous cleaning liquid of the scrubber 210.
[0034] The first used aqueous cleaning solution is converted by electrolysis into gaseous hydrogen H 2 and dissolved hydroxide ions OH - , and in the anode chamber 313, oxygen O 2 and carbon dioxide CO 2 This is indicated in FIG. 1 by the upward arrows from the cathode outlet 312″ and the anode outlet 313″, respectively. 2 and dissolved hydroxide ions OH - is drawn from the cathode chamber 312, and oxygen O 2 and carbon dioxide CO 2A gaseous mixture of hydrogen and hydrogen is withdrawn from the anode chamber 313. 2 may be used in downstream processes (not shown), such as for fuel or methanol production.
[0035] The regenerated alkaline aqueous cleaning solution from the cathode chamber 312 is then recycled to the scrubber 210 via an inlet 212' for receiving the alkaline aqueous cleaning solution. Carbon dioxide CO 2 The depleted gas exits the scrubber 210 via the scrubber outlet 214.
[0036] The gaseous mixture of carbon dioxide and oxygen withdrawn from the anode chamber 313 is transported to a separator 340, where substantially pure gaseous CO 2 Oxygen is removed from the gaseous mixture to obtain a stream of substantially pure gaseous CO. 2 may be transferred to a compression unit 330, where gaseous CO 2 is essentially pure liquid CO 2 is converted to
[0037] In addition, the regenerator 300 also regenerates oxygen O drawn from the anode chamber 313. 2 and carbon dioxide CO 2 The compressor unit 330 further comprises a first gas separator 340 for separating the refrigerant from the liquid. The first gas separator 340 is disposed upstream of the second compressor unit 330.
[0038] The composition of the gaseous mixture is typically approximately 75% v / v CO 2 and 25% v / v O 2 When the system 100 is in operation, oxygen O 2 and carbon dioxide CO 2 is separated in the first gas separation device 340 and produces substantially pure gaseous CO which can be compressed in the first compressor unit 330. 2 Leave the flow of CO in liquid phase. 2The advantage of supplying carbon dioxide gas in a compressed form is that it is practical during transportation. In this way, according to the invention, oxygen is removed from the gaseous mixture before the carbon dioxide is compressed.
[0039] When compressing carbon dioxide into liquid carbon dioxide, at least 50% of the oxygen is removed from the gaseous mixture, allowing for significant energy savings.
[0040] According to an alternative embodiment, at least 60% of the oxygen is removed from the mixture.
[0041] According to one embodiment, at least 80% of the oxygen is removed from the mixture.
[0042] According to one embodiment, at least 90% of the oxygen is removed from the mixture.
[0043] According to one embodiment, at least 95% of the oxygen is removed from the mixture.
[0044] According to one embodiment, at least 99% of the oxygen is removed from said gaseous mixture.
[0045] The gas separator 340, according to one embodiment, can be a heating device, which can be, for example, a burner where oxygen in the gaseous mixture is used as the oxygen source instead of air, producing pure CO which can be collected, cleaned and treated downstream of the separator. 2 A gas stream and water remain. The heating device can also be used with e.g. biogas, natural gas or H 2 It can be a generator for obtaining central or district heating and electricity, using either gas as input, CO 2 / O 2 The total flow of the gaseous mixture from the anode compartment outlet is used as the oxygen source. One alternative is to use H from the cathode compartment of the electrolyzer cell. 2 The idea is to use gas as an input.
[0046] According to another embodiment, the separator 340 separates the gas from CO 2In a process in which the oxidizer is scrubbed for CO, a gaseous mixture of carbon dioxide and oxygen is provided as the oxidizing agent or oxidant, and all of the oxidant is CO 2 Mixed with O 2 If the flue gas is intermittently pure CO 2 and therefore pure CO 2 can be compressed directly with limited pretreatment. As an example, gas-fired power generators use CO instead of air. 2 / O 2 and methane as fuel, so that the exhaust gas is pure CO 2 and water. Therefore, the resulting exhaust gas is pure CO since no nitrogen from the air is injected, which would produce NOx and N2 in the exhaust. 2 It is.
[0047] According to a third embodiment, the separation device 340 is a biological aerobic process, such as, for example, a wastewater treatment plant, which is in flow connection to either a regenerator or a location to which a gaseous mixture of oxygen and carbon dioxide is transported. The gaseous mixture is utilized in a wastewater treatment process such that the oxygen in the gaseous mixture is consumed as an oxidant, for example, through various enzymatic and bacterial reactions in the wastewater process. The purified CO 2 can be collected and compressed.
[0048] Reference is now made to the regeneration apparatus 300 of Figure 2. In addition to the electrolysis cell 310 and its components previously described in connection with Figure 1, the regeneration apparatus 300 further comprises a second compressor unit 320 for compressing hydrogen gas withdrawn from the cathode chamber 312.
[0049] The regenerator 300 also regenerates gaseous hydrogen H drawn from the cathode chamber 312. 2 and, for example, liquid aqueous potassium hydroxide, KOH.
[0050] Furthermore, the regenerator 300 comprises a separator 350, such as a filter. For example, the filter may be a reverse osmosis filter. This concentrator 350 is arranged downstream of the first gas separation unit 340. It is noted that the electrolysis cell may be sensitive to impurities in the fluids flowing through the anode and cathode chambers. Therefore, there may also be a separate cleaning unit (not shown) that serves to remove impurities, such as, for example, nitrogen oxides NOx and sulfur oxides SOx, from the used aqueous cleaning solution before it enters the electrolysis cell 310. As an example, the cleaning unit may include a filter for removing particulate matter. It is noted that in Figs. 1-2, the direction of the arrows corresponds to the direction of flow of the fluids circulating in the system 100. Furthermore, the lines of the arrows indicate fluid or flow communication between the elements of this system.
[0051] <Chemical Process> The solvent is then regenerated using electrochemistry in the regenerator 300. In general, the electrochemical reaction can be divided into two parts: an anodic reaction and a cathodic reaction. These reactions are described below.
[0052] <Anode> In the anode chamber 313, O 2 and CO 2 was generated in two different steps. First, at the anode, 4H + With O 2 Then, H + reduces the pH value of the solvent, and CO 2 At the same time, O 2 The two gases are generated, 2 and O 2 The overall reaction in the anode chamber 313 is as follows: 4×HCO 3 - →O 2 +4×CO 2 +2×H 2 O+4e - The reaction at the anode is as follows: 2×H 2 O → O 2 +4×H + +4e - This reaction causes a local decrease in pH. This decrease in pH is due to the 3 - / CO 2 Shift the equilibrium to the right, so that: 4×H + +4×HCO 3 - → 4×CO 2 +4×H 2 O This allows the release of gaseous CO from the solvent. 2 This results in the release of
[0053] <Cathode> At the cathode, OH - With H 2 This reaction produced useful H for downstream applications. 2 and hydroxide ions (OH - The cathode chamber reaction 312 is as follows: 4×H 2 O+4 - →2×H 2 +4×OH -
[0054] <Required power> The electrochemical reaction in the electrolysis cell 310 requires power. The actual power consumption will depend on the technological implementation of the process of the system 100. Assuming 100% efficiency, the minimum current required for the process can be calculated using Faraday's law of thermodynamics: I=mFz / tM. The current can be calculated using the parameters listed in Table 1 below.
[0055] [Table 1]
[0056] Therefore, the current is I = 2.18 x 10 9 A. Assuming a minimum voltage of 2V, one ton of CO 2 The theoretical minimum power consumption for is: P min =2V×2.18×10 9 A = 2.18 x 10 9 J=4.36GJ
[0057] Higher energy consumption would be expected in real chemical reactions. As suggested by experimental models, CO 2 The final power consumption for the capture and solvent regeneration is 1 tonne of CO 2 The process regenerates the solvent and generates 5.88 GJ per unit of hydrogen at the cathode 312. 2 At the anode, CO 2 and O 2 The CO from the first gas separation device 340 produces a mixture of 2 and O 2 Separation of the two requires additional energy.
[0058] CO 2 and H 2 is typically produced in a ratio of 2:1. If the downstream application is methanol production, the preferred stoichiometric ratio is 1:3, and the process does not require additional H 2 A commercial electrolysis machine requires 55 kWh / kg of energy and is H 2 Therefore, one ton of CO 2 In the case of H 2 The required amount of (m co2 M co2 ) × 3 = 68182 mol, which is equal to 68182 mol × 2 g / mol × 55 kWh / kg = 7500 kWh = 26.98 GJ. The carbon capture and regeneration process produces the equivalent of 4.5 GJ of H 2 and therefore H 2 The remaining energy requirement for production is 26.98GJ-4.50GJ=22.48GJ. The power consumption of the carbon capture process is determined primarily by the electrochemical cell.2 The purification of ethanol requires additional energy.
[0059] [CO 2 When CO is removed from the gas stream 2 Improving compressor efficiency CO 2 The liquefaction or compression of CO requires energy, where the energy can be in the form of electricity for a compressor. Typically, CO 2 is transported in its liquid state at 15 bar and -30°C. Pure CO 2 Optimized compression and liquefaction of CO typically requires approximately 110wh / kg CO 2 The other components are CO 2 If present, the cost of compression would increase due to the increased volume and weight.
[0060] CO exiting the system 100 according to the present disclosure 2 Flow rate is 66% v / v~80% v / v CO 2 With content of CO 2 and O 2 and thus, CO 2 The energy required to compress a stream of pure CO 2 The energy is higher than that of
[0061] Tests and calculations performed based on non-adiabatic compression and subsequent condensation showed that CO 2 and O 2 CO with both 2 The optimum energy requirement for compressing the mixed stream is CO 2 The content of is about 80% v / v, and O 2 is about 20% v / v, then about 160wh / kg CO 2 Therefore, CO 2 20% v / v O in the mixed stream 2 reduces energy consumption to approximately 110wh / kg CO 2 to 160wh / kg CO 2, which is an increase of at least 50wh / kg.
[0062] Therefore, CO 2 Mixed flow O 2 The reduction in content results in a significant reduction in energy usage, thereby reducing the amount of CO 2 leaving the system 100 of the present disclosure. 2 This reduces the cost of compressing the
[0063] [Experimental section] <Example 1> Below, we consider the CO2 emissions from a 10MW biomass-fired heat and power plant. 2 The capture is presented in terms of three process steps: "scrubber", "regeneration" and "separation". Overall, the process requires a large amount of electrical energy. Electrification of the carbon capture process is highly desired and is entirely new, so a large amount of electrical energy is a positive. Part of the energy can be recovered as heat for district heating.
[0064] [Table 2]
[0065] <Example 2> Laboratory tests were conducted to verify the applicability of the process using the system 100 described herein.
[0066] For laboratory testing, a standard electrolysis cell from EC Electrocell, model Electro MP Cell, was used. The electrolysis cell was equipped with a Nafion 117 membrane. The cell was operated in 1.5 M KHCO 3The solution was circulated over the anode side from a combined degassing / circulation tank. The liquid was circulated at 1.5 L / min. Similarly, a 1.5 M KOH solution was circulated over the cathode side from a combined degassing / circulation tank. The liquid was circulated at 1.5 L / min. Standard flow meters and laboratory pumps were used. The gas flow from the degassing tank was measured by an Aalborg GFM gas flow meter. CO 2 The content was measured using a Guardian NG from Edinburgh Sensors. A standard heating plate was used to keep the liquid at a constant temperature of 40 degrees Celsius during the experiment. pH and temperature were measured in the circulating tank using a standard online pH meter and thermometer. The current density applied to the electrolytic cell was measured using a standard power converter in the range of 1-4 kA / m 2 The results were varied between 0.01 and 0.1.
[0067] <Example 3> Detailed data from single cell testing Tests were carried out to verify the applicability of the process using the system 100 described herein. The tests were carried out with commercially available components from Electrocell, typically used for the production of KOH and chlorine. The cell was of the Electro MP Cell type from Electrocell A / S, Vennelystvej 1, DK-6880 Tarm, with the following configuration: the anode was titanium coated with MMO, the cathode was made of nickel alloy, and the membrane was a Nafion 424 membrane.
[0068] CO 2 is equivalent to a fully filled absorption solution of 0.6M KHCO 3 The test was carried out in a solution, and the absorbent was circulated to the anode side of the cell at 1.5 l / min. 2 The content depends on the effectiveness of the scrubber. Tests have been carried out and the absorbent has shown that it can reduce the amount of CO 2 At least 90% of the absorption was achieved.
[0069] Over the cathode, 4.5M KOH is circulated at 1.5 l / min to increase the KOH concentration and the bleed-out liquid from the cathode is equivalent to the lean absorbent liquid.
[0070] The temperature of the cell and the liquid stream was set at 70° C. A voltage was then applied to the cell and increased until a current of 15 A was reached for the total current-voltage relationship of the cell, as seen in FIG.
[0071] As can be seen in Figure 4, CO released from the anode 2 The amount of CO was measured using a mass flow meter and 2 The CO2 sensor was measured and Figure 4 shows the current-voltage (4 V at 15 A) curves as a function of time during which 2 The concentrations and gas flows are shown. The flowmeters used are of the Aalborg GFM gas flowmeter type, and the CO 2 The meter is a Guardian NG type from Edinburgh Sensors. 2 The mixed stream is approximately 78% v / v CO 2 It can be seen that the content is
Claims
1. Carbon dioxide (CO ２ ) and oxygen (O ２ 1. A method for preparing substantially pure gaseous carbon dioxide from a gaseous mixture of carbon dioxide and a water-soluble polymer, the method comprising the steps of: the gaseous mixture is withdrawn from the anode chamber (313) of an electrolytic cell (310), the electrolytic cell (310) being supplied with spent aqueous scrubbing liquid from a scrubber (210), the scrubber (210) scrubbing the gas having a first carbon dioxide concentration with a first alkaline aqueous scrubbing liquid; the spent aqueous cleaning solution is regenerated in the electrolysis cell (310) by electrolysis; The regeneration is carried out by adding oxygen (O ２ ) and carbon dioxide (CO ２ ) and generating a gaseous mixture with The gaseous mixture contains 66-80% v / v carbon dioxide (CO ２ ) and 20% v / v to 34% v / v oxygen (O ２ ) and The method comprises: The oxygen and carbon dioxide (CO ２ treating the gaseous mixture with HCl to remove at least 50% of the oxygen from the gaseous mixture; A method comprising:
2. 2. The method of claim 1, wherein at least 60% of the oxygen is removed from the gaseous mixture, or at least 70% of the oxygen is removed from the gaseous mixture, or at least 80% of the oxygen is removed from the gaseous mixture, or at least 90% of the oxygen is removed from the gaseous mixture, or at least 95% of the oxygen is removed from the gaseous mixture, or at least 99% of the oxygen is removed from the gaseous mixture.
3. 3. The method of claim 1 or 2, further comprising compressing the oxygen-depleted gaseous mixture into substantially pure liquid carbon dioxide.
4. 3. The method of claim 1, wherein the gas having the first carbon dioxide concentration is one of a flue gas, an exhaust gas, and air.
5. treating the gaseous mixture to remove at least 50% of the oxygen from the gaseous mixture, The gaseous mixture is passed through a heating device, thereby consuming the oxygen and producing carbon dioxide and dihydrogen oxide (H ２ generating an output stream of The method of claim 1 or 2, comprising:
6. 6. The method of claim 5, wherein the heating device is supplied with a fuel, the fuel being one of hydrogen, natural gas, or biogas.
7. 6. The method of claim 5, wherein the hydrogen is gaseous hydrogen withdrawn from the cathode compartment of the electrolysis cell (313).
8. treating the gaseous mixture to remove at least 50% of the oxygen from the gaseous mixture, CO ２ Utilizing the gaseous mixture as an oxidizing agent in a process step for scrubbing flue gases. The method of claim 1 or 2, comprising:
9. treating the gaseous mixture to remove at least 50% of the oxygen from the gaseous mixture, 3. The method of claim 1 or 2, comprising utilizing the gaseous mixture as an oxidant in an aerobic biological process facility.
10. 1. A system for scrubbing a gas, such as a flue gas or exhaust gas, containing carbon dioxide to deplete the carbon dioxide from the flue gas, the system comprising: a scrubber unit (200) for scrubbing gases with an alkaline aqueous scrubbing liquid, comprising a scrubber (210); a regeneration device (300) for regenerating the used aqueous cleaning liquid by electrolysis, wherein: - said regeneration device comprises an electrolysis cell (310) comprising an anode chamber (313) with an anode inlet (313') for receiving said used aqueous cleaning liquid and an anode outlet (313'') for withdrawing oxygen and carbon dioxide; wherein said scrubber (210) is in flow communication with said electrolysis cell (310); a gas separator (340) for separating the oxygen and carbon dioxide extracted from the anode chamber (313) from each other; a compressor unit (330) for compressing the substantially pure carbon dioxide withdrawn from the separation device (340); A system comprising:
11. 1. A regeneration apparatus for regenerating a used aqueous cleaning solution to provide an alkaline aqueous cleaning solution, said regeneration apparatus (300) comprising an electrolysis cell (310) having an anode chamber (313) with an anode inlet (313′) for receiving said used aqueous cleaning solution and an anode outlet (313″) for withdrawing oxygen and carbon dioxide, wherein a cathode chamber (312) has an outlet (312″) for withdrawing regenerated aqueous cleaning solution; a gas separator (340) for separating oxygen and carbon dioxide from each other from said anode chamber (313); a compressor unit (330) for compressing the carbon dioxide withdrawn from said first gas separation device (340); A playback device comprising:
12. 12. The system of claim 10 or claim 11, wherein the gas separation device (340) is a heating device.
13. 12. The system of claim 10 or claim 11, wherein the gas separation device (340) is an aerobic biological process facility.
14. 12. The system of claim 10 or claim 11, wherein in the gas separation device (340) at least 50% of the oxygen is removed from the gaseous mixture of carbon dioxide and oxygen withdrawn from the anode chamber.
15. 15. The system of claim 14, wherein at least 60% of the oxygen is removed from the gaseous mixture, or at least 70% of the oxygen is removed from the gaseous mixture, or at least 80% of the oxygen is removed from the gaseous mixture, or at least 90% of the oxygen is removed from the gaseous mixture, or at least 95% of the oxygen is removed from the gaseous mixture, or at least 99% of the oxygen is removed from the gaseous mixture.