Method for finely removing NOx from carbon dioxide gas source

Abstract

The invention discloses a method for finely removing NOx from a carbon dioxide gas source, and belongs to the technical field of carbon dioxide purification. According to the method, O2, water vapor and NOx in ammonia gas and the carbon dioxide gas source are subjected to an oxidation reaction to generate nitrate and / or nitrite, and ammonia salt is adsorbed on a wet interface to remove NOx in the carbon dioxide gas source; specifically, a gas loop between a first reaction cavity and a second reaction cavity is formed by changing a reaction cavity for inputting a carbon dioxide gas source and ammonia gas, cooperatively changing an oxidation reaction and a reduction reaction in the first reaction cavity and the second reaction cavity, and transmitting part of NOx-removed gas through a first channel and transmitting ammonia gas through a second channel; according to the invention, NOx in the carbon dioxide gas source is removed, the reduction reaction for generating ammonia gas is alternately and circularly carried out in the first reaction cavity and the second reaction cavity respectively, and continuous NOx removal treatment on the carbon dioxide gas source can be realized, so that the residual amount of NOx in the output gas can reach the standard of food-grade carbon dioxide.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide purification, and particularly relates to a method for precisely removing NOx from a carbon dioxide gas source. Background Art

[0002] Carbon dioxide is a valuable resource that can be widely applied in various fields. A large amount of carbon dioxide is required in industries such as chemical synthesis industry, mechanical protection welding, metal casting processing, agricultural fertilization, fresh-keeping of fruits and vegetables, beer and beverage filling, oil extraction, fire extinguishing, and medicine and health. Due to the ineffective measures for recovering carbon dioxide, the recycled carbon dioxide each year is less than 1% of the emissions, which not only causes air pollution and forms a terrible greenhouse effect, but also wastes precious resources.

[0003] Currently, the purification of carbon dioxide usually adopts adsorption materials such as activated carbon. Since there is no good selective adsorption material specifically for NO x , the targeting is poor, and it cannot ensure that the residual amount of NO in the CO2 gas after adsorption can meet the standard of food-grade carbon dioxide. In addition, there is also a method of removing NO in CO2 by low-temperature rectification process x , but the rectification tower is expensive and the economy is poor. x Summary of the Invention

[0004] In view of one or more of the above defects or improvement requirements in the prior art, the present invention provides a method for precisely removing NOx from a carbon dioxide gas source, which can realize continuous NOx removal treatment of a carbon dioxide gas source containing CO2, NOx, N2, O2, and water vapor, so that the residual amount of NOx in the output gas can meet the standard of food-grade carbon dioxide, with high efficiency and better economy.

[0005] To achieve the above object, the present invention provides a method for precisely removing NOx from a carbon dioxide gas source for preparing food-grade carbon dioxide. The carbon dioxide gas source contains CO2, NOx, N2, O2, and water vapor, and it includes the following steps: S1: Input the carbon dioxide gas source and excessive ammonia into the first reaction chamber and form a wet interface in the first reaction chamber; NOx undergoes an oxidation reaction in the first reaction chamber and is converted into nitrates and / or nitrites adsorbed on the wet interface, completing the removal of NOx from the carbon dioxide gas source; Input the gas after removing NOx in the first reaction chamber into the second reaction chamber; S2: Input the carbon dioxide gas source into the second reaction chamber and form a wet interface in the second reaction chamber; NOx undergoes an oxidation reaction in the second reaction chamber and is converted into nitrates and / or nitrites adsorbed on the wet interface, completing the removal of NOx from the carbon dioxide gas source. Part of the gas after removing NOx from the second reaction chamber is input into the first reaction chamber along the first channel, and part is discharged; meanwhile, the nitrates and nitrites in the first reaction chamber undergo a reduction reaction to generate ammonia, and the ammonia in the first reaction chamber is input into the second reaction chamber along the second channel to participate in the process of converting NOx into nitrates and / or nitrites; S3: Input the carbon dioxide gas source into the first reaction chamber and form a wet interface in the first reaction chamber; NOx undergoes an oxidation reaction in the first reaction chamber and is converted into nitrates and / or nitrites adsorbed on the wet interface, completing the removal of NOx from the carbon dioxide gas source. Part of the gas after removing NOx from the first reaction chamber is input into the second reaction chamber along the first channel, and part is discharged; meanwhile, the nitrates and nitrites in the second reaction chamber undergo a reduction reaction to generate ammonia, and the ammonia in the second reaction chamber is input into the first reaction chamber along the second channel to participate in the process of converting NOx into nitrates and / or nitrites; S4: Repeat the loop steps S2 - S3 until all of the carbon dioxide gas source has completed the precise removal of NOx.

[0006] As a further improvement of the present invention, the method for precisely removing NOx from the carbon dioxide gas source further includes: detecting the NOx content of the discharged gas after removing NOx to determine whether it meets the standard of food - grade carbon dioxide.

[0007] As a further improvement of the present invention, the method for precisely removing NOx from the carbon dioxide gas source further includes: passing the discharged gas after removing NOx through a water washing and dehydration device for de - ammoniation treatment.

[0008] As a further improvement of the present invention, steps S1, S2, and S3 can be continuously carried out for a predetermined time respectively.

[0009] As a further improvement of the present invention, the oxidation reaction and the reduction reaction are carried out in the following manner: In the first reaction chamber, a number of first anode plates and a number of first cathode plates are arranged in parallel at intervals and alternately; in the second reaction chamber, a number of second anode plates and a number of second cathode plates are arranged in parallel at intervals and alternately. Connect the positive pole of the power supply to the first anode plate / second anode plate for the oxidation reaction, and connect the negative pole of the power supply to the first cathode plate / second cathode plate for the reduction reaction.

[0010] As a further improvement of the present invention, the method for precisely removing NOx from the carbon dioxide gas source further includes: inputting electrons into the carbon dioxide gas source before introducing the carbon dioxide gas source into the first reaction chamber / second reaction chamber.

[0011] As a further improvement of the present invention, the way of forming the wet interface is as follows: a conductive catalyst adsorbent is filled between adjacent first anode plates and first cathode plates, and a conductive catalyst adsorbent is filled between adjacent second anode plates and second cathode plates, and the conductive catalyst adsorbent absorbs water vapor in the carbon dioxide gas source to form a wet interface.

[0012] As a further improvement of the present invention, the conductive catalyst adsorbent is composed of basic magnesium carbonate, a catalyst component and metal foam. Among them, the basic magnesium carbonate is a carrier for absorbing NOx, the catalyst component is composed of Fe2TiO5, Zn, and ZnO, and the metal foam is a conductive substrate.

[0013] As a further improvement of the present invention, the method for precisely removing NOx from the carbon dioxide gas source further includes: before introducing the carbon dioxide gas source into the first reaction chamber / second reaction chamber, detecting the water vapor content of the carbon dioxide gas source, and if the water vapor content is insufficient, inputting a certain amount of water vapor into the carbon dioxide gas source.

[0014] As a further improvement of the present invention, a conductive catalyst adsorbent is also filled between the outermost first anode plate / first cathode plate and the first reaction chamber; and / or, a conductive catalyst adsorbent is also filled between the outermost second anode plate / second cathode plate and the second reaction chamber.

[0015] The above improved technical features can be combined with each other as long as they do not conflict with each other.

[0016] Generally speaking, compared with the prior art, the beneficial effects of the above technical solutions conceived by the present invention include: (1) In the method for precisely removing NOx from the carbon dioxide gas source of the present invention, ammonia, O2, water vapor, and NOx in the carbon dioxide gas source are used for an oxidation reaction to generate nitrates and / or nitrites, and ammonium salts are adsorbed on the wet interface to remove NOx in the carbon dioxide gas source; specifically, by changing the reaction chambers of the carbon dioxide gas source, cooperating with changing the oxidation reaction and reduction reaction in the first reaction chamber and the second reaction chamber, and using the first channel to transmit part of the gas after removing NOx and the second channel to transmit ammonia to form a gas circuit between the first reaction chamber and the second reaction chamber, the removal of NOx in the carbon dioxide gas source and the reduction reaction of generating ammonia are alternately and cyclically carried out in the first reaction chamber and the second reaction chamber respectively, so as to continuously carry out the NOx removal treatment on the carbon dioxide gas source, enabling the remaining amount of NOx in the output gas to meet the standard of food-grade carbon dioxide, with high NOx removal efficiency and good economy.

[0017] (2) In the method for precisely removing NOx from a carbon dioxide gas source according to the present invention, electrons are input into the carbon dioxide gas source before it is introduced into the first reaction chamber / the second reaction chamber to improve the activity and conductivity of the carbon dioxide gas source, and it can also activate the catalyst activity. Moreover, when electrons collide with and are absorbed by metal materials such as electrodes and catalysts in the first reaction chamber / the second reaction chamber, the metal materials can be heated, the temperature inside the tower can be increased, the reaction rate can be accelerated, and the efficiency of removing NOx can be improved.

[0018] (3) In the method for precisely removing NOx from a carbon dioxide gas source according to the present invention, water vapor is input into the carbon dioxide gas source before it is introduced into the first reaction chamber / the second reaction chamber to make up for the insufficient water content in the carbon dioxide gas source. An appropriate water vapor content can not only increase the conductivity of the carbon dioxide gas source but also be conducive to creating the humid interface required for the electrochemical reaction. Brief Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 is a flowchart of the method for precisely removing NOx from a carbon dioxide gas source in an embodiment of the present invention.

[0021] Figure 2 is a schematic diagram of a CO2 purification system for precisely removing NOx based on electrocatalytic oxidation-reduction adsorption in an embodiment of the present invention.

[0022] In all the drawings, the same reference numerals represent the same technical features, specifically: 1. First tower body; 101. First anode plate; 102. First cathode plate; 2. Second tower body; 201. Second anode plate; 202. Second cathode plate; 3. Electrocatalytic power supply; 4. Feed pipe; 5. Discharge pipe; 6. Feeding pipe; 601. First feeding pipeline; 6011. First valve; 602. Second feeding pipeline; 6021. Second valve; 7. Supply pipe; 701. First supply pipeline; 7011. Third valve; 702. Second supply pipeline; 7021. Fourth valve; 8. Return pipe; 801. Fifth valve; 802. Sixth valve; 9. Siphon three-way joint; 901. First inlet; 902. Second inlet; 903. Outlet; 10. Electron beam generator; 11. Water vapor supply pipe; 12. First analysis indicator; 13. Second analysis indicator; 14. Pressure indicator; 15. Temperature indicator; 16. Differential pressure detection meter. Detailed Embodiments

[0023] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0025] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0026] In the present invention, unless otherwise clearly defined and limited, the terms "mounted", "connected", "coupled", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0028] Example

[0029] Please refer to Figure 1 , in the method for precise removal of NOx from a carbon dioxide gas source in a preferred embodiment of the present invention, which is used to prepare food-grade carbon dioxide, the carbon dioxide gas source contains CO2, NOx, N2, O2, and water vapor, and includes the following steps: S1: Input the carbon dioxide gas source and excessive ammonia into the first reaction chamber and form a humid interface in the first reaction chamber; NOx undergoes an oxidation reaction in the first reaction chamber and is converted into nitrates and / or nitrites adsorbed on the humid interface, completing the removal of NOx from the carbon dioxide gas source; Input the gas after removing NOx from the first reaction chamber into the second reaction chamber; S2: Input the carbon dioxide gas source into the second reaction chamber and form a humid interface in the second reaction chamber; NOx undergoes an oxidation reaction in the second reaction chamber and is converted into nitrates and / or nitrites adsorbed on the humid interface, completing the removal of NOx from the carbon dioxide gas source. Part of the precisely removed reaction gas in the second reaction chamber is input into the first reaction chamber along the first channel, and part is discharged; At the same time, the nitrates and nitrites in the first reaction chamber undergo a reduction reaction to generate ammonia, and the ammonia in the first reaction chamber is input into the second reaction chamber along the second channel to participate in the process of converting NOx into nitrates and / or nitrites; S3: Input the carbon dioxide gas source into the first reaction chamber and form a humid interface in the first reaction chamber; NOx undergoes an oxidation reaction in the first reaction chamber and is converted into nitrates and / or nitrites adsorbed on the humid interface, completing the removal of NOx from the carbon dioxide gas source. Part of the precisely removed reaction gas in the first reaction chamber is input into the second reaction chamber along the first channel, and part is discharged; At the same time, the nitrates and nitrites in the second reaction chamber undergo a reduction reaction to generate ammonia, and the ammonia in the second reaction chamber is input into the first reaction chamber along the second channel to participate in the process of converting NOx into nitrates and / or nitrites; S4: Repeat the loop steps S2~S3 until all the carbon dioxide gas source has completed the precise removal of NOx.

[0030] Among them, NOx includes NO and NO2. NO undergoes an oxidation reaction to generate nitrite, and NO2 undergoes an oxidation reaction to generate nitrate. Since the ammonia input into the first reaction chamber in step S1 is excessive, the gas after removing NOx from the first reaction chamber in step S1 still contains ammonia. When NOx in one reaction chamber is converted into nitrates and / or nitrites in steps S2 and S3, a part of the ammonia is consumed, and at the same time, ammonia is generated and replenished in the other reaction chamber. Therefore, the gas after removing NOx from the first reaction chamber / second reaction chamber in steps S2 and S3 also still contains ammonia.

[0031] The method for precisely removing NOx from a carbon dioxide gas source of the present invention uses ammonia, O2, water vapor, and NOx in the carbon dioxide gas source to carry out an oxidation reaction to generate nitrates and / or nitrites, and ammonium salts are adsorbed on a wet interface to remove NOx from the carbon dioxide gas source. Moreover, the ammonia gas generated during the reduction reaction of the nitrates and / or nitrites and ammonium salts can also quickly enter and exit the wet interface phase state. By changing the reaction chamber into which the carbon dioxide gas source and ammonia gas are input, cooperating with changing the oxidation reaction and reduction reaction in the first reaction chamber and the second reaction chamber, and using the first channel to transport part of the gas after removing NOx and the second channel to transport ammonia gas to form a gas loop between the first reaction chamber and the second reaction chamber, the removal of NOx from the carbon dioxide gas source and the reduction reaction generating ammonia gas are alternately carried out in the first reaction chamber and the second reaction chamber respectively, so that continuous NOx removal treatment of the carbon dioxide gas source can be realized, the efficiency of removing NOx is high, and the economy is relatively good.

[0032] Preferably, steps S1, S2, and S3 can be continuously carried out for a predetermined time respectively. The predetermined time can be comprehensively calculated according to the NOx content in the introduced carbon dioxide gas source, the content of the catalyst in the first reaction chamber / second reaction chamber, the content of the reducing gas, and the electrochemical reaction rate, etc., so that NOx in the carbon dioxide gas source can be fully adsorbed and removed within this predetermined time period. In a specific embodiment, the predetermined time can be 30s - 60s, 1 minute, 2 minutes, etc.

[0033] Since the gas after removing NOx discharged carries part of ammonia gas, therefore, the method for precisely removing NOx from a carbon dioxide gas source of the present invention preferably further includes: introducing the gas after removing NOx discharged into a water washing and dehydration device for ammonia removal treatment.

[0034] Preferably, the method for precisely removing NOx from a carbon dioxide gas source of the present invention further includes: detecting the NOx content of the gas after removing NOx discharged to judge whether it meets the standard of food-grade carbon dioxide.

[0035] Further preferably, the oxidation reaction and the reduction reaction are carried out in the following manner: A number of first anode plates and a number of first cathode plates are arranged in parallel at intervals alternately in the first reaction chamber, and a number of second anode plates and a number of second cathode plates are arranged in parallel at intervals alternately in the second reaction chamber. The positive electrode of the power supply is connected to the first anode plate / second anode plate for the oxidation reaction, and the negative electrode of the power supply is connected to the first cathode plate / second cathode plate for the reduction reaction.

[0036] Preferably, the wet interface is formed in the following way: a conductive catalyst adsorbent is filled between adjacent first anode plates and first cathode plates, and a conductive catalyst adsorbent is filled between the adjacent second anode plates and the second cathode plates. The conductive catalyst adsorbent absorbs water vapor in the carbon dioxide gas source to form a wet interface.

[0037] Further preferably, a conductive catalyst adsorbent is also filled between the outermost first anode plate / first cathode plate and the first reaction chamber; a conductive catalyst adsorbent is also filled between the outermost second anode plate / second cathode plate and the second reaction chamber.

[0038] Furthermore, the method for precisely removing NOx from a carbon dioxide gas source according to the present invention further includes: before introducing the carbon dioxide gas source into the first reaction chamber / second reaction chamber, electrons are input into the carbon dioxide gas source. On the one hand, it can improve the activity and conductivity of the carbon dioxide gas source, and on the other hand, it can also activate the catalyst. Moreover, when electrons collide and are absorbed by metal materials such as electrodes and catalysts in the first reaction chamber / second reaction chamber, the metal materials can be heated, the temperature inside the tower can be increased, and the reaction rate can be accelerated.

[0039] When the water vapor content in the carbon dioxide gas source is low, it is necessary to add water vapor to the carbon dioxide gas source to increase the conductivity of the gas. An appropriate water vapor content can not only increase the conductivity of the carbon dioxide gas source but also help create the humid interface required for the electrochemical reaction.

[0040] Preferably, the method for precisely removing NOx from a carbon dioxide gas source according to the present invention further includes: before introducing the carbon dioxide gas source into the first reaction chamber / second reaction chamber, detecting the water vapor content of the carbon dioxide gas source. If the water vapor content is insufficient, a certain amount of water vapor is input into the carbon dioxide gas source.

[0041] Preferably, the conductive catalyst adsorbent is composed of basic magnesium carbonate, a catalyst component, and metal foam. Among them, basic magnesium carbonate is the carrier for absorbing NOx, the catalyst component is composed of Fe2TiO5, Zn, and ZnO, and the metal foam is the conductive substrate.

[0042] In this embodiment, initially, basic magnesium carbonate absorbs CO2 in the carbon dioxide gas source to form bicarbonate until it no longer absorbs. The bicarbonate acts with water vapor and ionizes to be weakly alkaline; the components of Fe2TiO5, Zn, and ZnO in the catalyst are preferably in a ratio of 1:1:1; the metal foam preferably uses titanium metal foam.

[0043] The following specific preferred embodiment is an electrocatalytic oxidation-reduction adsorption precise NOx removal system for CO2 purification to implement this method.

[0044] Please refer to Figure 2 , the CO2 purification system based on electrocatalytic oxidation-reduction adsorption precise NOx removal in the preferred embodiment includes a first tower body 1, a second tower body 2, an electrocatalytic power supply 3, a feed pipe 4, a discharge pipe 5, a feeding pipe 6, a supply pipe 7, a return pipe 8, and a siphon three-way joint 9. Among them, the first tower body 1 and the second tower body 2 respectively correspond to the first reaction chamber and the second reaction chamber in this method.

[0045] Specifically, the siphon three-way joint 9 includes a first inlet 901, a second inlet 902, and an outlet 903. A Venturi tube structure is provided between the first inlet 901 and the outlet 903 of the siphon three-way joint 9; the first inlet 901 of the siphon three-way joint 9 is connected to the feed pipe 4, and the feed pipe 4 is used to input a carbon dioxide gas source; the outlet 903 is connected to the feed pipe 6, and the feed pipe 6 includes a first feed pipe 601 and a second feed pipe 602 that can be controlled to open and close, and are used to provide a carbon dioxide gas source for the first tower body 1 and the second tower body 2 respectively; the second inlet 902 is connected to the supply pipe 7, and the supply pipe 7 includes a first supply pipe 701 and a second supply pipe 702 that can be controlled to open and close, and are used to provide a reducing gas for the first tower body 1 and the second tower body 2 respectively; the return pipe 8 connects the top of the first tower body 1 and the top of the second tower body 2, and a discharge pipe 5 is further connected to the return pipe 8, which is used to transport the output gas after NOx removal.

[0046] In this embodiment, the Venturi tube structure adopted by the siphon three-way joint 9 enables gas to enter from the first inlet 901 and the second inlet 902 and be output from the outlet 903 to ensure the direction of gas transmission.

[0047] Preferably, the first feed pipe 601, the second feed pipe 602, the first supply pipe 701, and the second supply pipe 702 are respectively controlled to open and close through a first valve 6011, a second valve 6021, a third valve 7011, and a fourth valve 7021.

[0048] Further, a number of first anode plates 101 and a number of first cathode plates 102 are arranged in parallel and alternately at intervals in the first tower body 1, and a conductive catalyst adsorbent is filled between adjacent first anode plates 101 and first cathode plates 102; a number of second anode plates 201 and a number of second cathode plates 202 are arranged in parallel and alternately at intervals in the second tower body 2, and a conductive catalyst adsorbent is filled between adjacent second anode plates 201 and second cathode plates 202. The conductive catalyst adsorbent can absorb water vapor in the carbon dioxide gas source to form a wet interface; the electrocatalytic power supply 3 can be electrically connected to the first anode plate 101, the first cathode plate 102, the second anode plate 201, and the second cathode plate 202 respectively to provide electrical energy for the electrochemical reactions in the first tower body 1 and the second tower body 2, so that the oxidation reaction of the anode plate and the reduction reaction of the cathode plate can be alternately carried out in the first tower body 1 and the second tower body 2 respectively. Among them, the reduction reaction is used to generate a reducing gas, and the oxidation reaction causes NOx in the carbon dioxide gas source and the reducing gas to be converted into nitrates and / or nitrites at the wet interface. The nitrates and nitrites are ionized to form nitrate ions and nitrite ions, which are adsorbed on the wet interface to complete the removal of NOx.

[0049] Preferably, before the system is first operated, a reducing gas needs to be introduced into both the first tower body 1 and the second tower body 2.

[0050] Exemplarily, the operation process of the present system for specifically removing NOx from a carbon dioxide gas source is as follows: Open the first valve 6011 and the fourth valve 7021, close the second valve 6021 and the third valve 7011, and connect the positive and negative electrodes of the electrocatalytic power supply 3 to the first anode plate 101 and the second cathode plate 202 respectively. The carbon dioxide gas source is input from the inlet of the feed pipe 4 and enters the first tower body 1 through the siphon three-way joint 9 and the first feed pipe 601. The reducing gas in the second tower body 2 can also enter the first tower body 1 through the second supply pipe 702, the siphon three-way joint 9, and the first feed pipe 601. The conductive catalyst adsorbent in the first tower body 1 absorbs the water vapor in the carbon dioxide gas source to form a wet interface. NOx, water vapor, and O2 in the carbon dioxide gas source undergo an oxidation reaction to produce nitric acid and / or nitrous acid. Nitric acid or nitrous acid further reacts with the reducing gas to produce nitrates and / or nitrites. The nitrates and / or nitrites ionize to form nitrate ions and nitrite ions, which are adsorbed on the wet interface, completing the removal of NOx. At this time, the gas after removing NOx in the first tower body 1 still contains the reducing gas. Part of it is discharged along the discharge pipe 5, and the other part enters the second tower body 2 through the return pipe 8 to continue pushing the reducing gas in the second tower body 2 into the first tower body 1 for replenishment, so that the continuously entering carbon dioxide gas source in the first tower body 1 can continue to complete the removal of NOx; Further, close the first valve 6011 and the fourth valve 7021, open the second valve 6021 and the third valve 7011, and connect the positive and negative electrodes of the electrocatalytic power supply 3 to the second anode plate 201 and the first cathode plate 102 respectively. The carbon dioxide gas source is input from the inlet of the feed pipe 4 and enters the second tower body 2 through the siphon three-way joint 9 and the second feed pipe 602. At this time, the nitrates and nitrites in the first tower body 1 undergo a reduction reaction to produce the reducing gas, and this reducing gas also enters the second tower body 2 through the first supply pipe 701, the siphon three-way joint 9, and the second feed pipe 602. The conductive catalyst adsorbent in the second tower body 2 absorbs the water vapor in the carbon dioxide gas source to form a wet interface. NOx, water vapor, and O2 in the carbon dioxide gas source undergo an oxidation reaction to produce nitric acid or nitrous acid. Nitric acid or nitrous acid further reacts with the reducing gas to produce nitrates and / or nitrites. The nitrates and / or nitrites ionize to form nitrate ions and / or nitrite ions, which are adsorbed on the wet interface, completing the removal of NOx. At this time, the gas after removing NOx in the second tower body 2 still contains the reducing gas. Part of it is discharged along the discharge pipe 5, and the other part enters the first tower body 1 through the return pipe 8 to continue pushing the reducing gas in the first tower body 1 into the second tower body 2 for replenishment, so that the continuously entering carbon dioxide gas source in the second tower body 2 can continue to complete the removal of NOx; By continuously changing the connection mode of the electrocatalytic power supply 3 and the opening and closing conditions of the first valve 6011, the fourth valve 7021, the second valve 6021, and the third valve 7011, the oxidation reaction and the reduction reaction continue to alternate and circulate in the first tower body 1 and the second tower body 2, so as to continuously carry out the NOx removal treatment on the carbon dioxide gas source.

[0051] This system guides the flow directions of the carbon dioxide gas source and the reducing gas through the channel control of the feed pipe 6 and the supply pipe 7, controls the electrochemical reactions in the first tower body 1 and the second tower body 2 through the electrocatalytic power supply 3, and forms a gas flow loop between the first tower body 1 and the second tower body 2 by using the gas after partial NOx removal and the reducing gas, so that the NOx adsorption reaction of the carbon dioxide gas source alternates and circulates on the conductive catalyst adsorbent in the first tower body 1 and the second tower body 2, so as to continuously carry out the NOx removal treatment on the carbon dioxide gas source, and make the remaining amount of NOx in the output gas reach the standard of food-grade carbon dioxide. This system is used for the precise NOx removal of the carbon dioxide gas source, with high efficiency and good economy.

[0052] Preferably, the outermost first anode plate 101 / first cathode plate 102 and the first tower body 1 are also filled with a conductive catalyst adsorbent; the outermost second anode plate 201 / second cathode plate 202 and the second tower body 2 are also filled with a conductive catalyst adsorbent.

[0053] Preferably, an electron beam generator 10 is arranged on the feed pipe 4, which is used to output electrons into the carbon dioxide gas source to improve the activity and conductivity of the carbon dioxide gas source, and can also stimulate the activity of the catalyst. At the same time, the collision and absorption of electrons with metal materials such as electrodes and catalysts in the first tower body 1 / second tower body 2 can also heat the metal materials, increase the temperature in the tower, and accelerate the reaction rate.

[0054] Preferably, the conductive catalyst adsorbent is composed of basic magnesium carbonate, a catalyst, and metal foam. Among them, basic magnesium carbonate is the carrier for absorbing NOx, the catalyst is composed of Fe2TiO5, Zn, and ZnO, and the metal foam is the conductive substrate.

[0055] In this embodiment, basic magnesium carbonate initially absorbs CO2 in the carbon dioxide gas source to form bicarbonate until it no longer absorbs, and the bicarbonate ionizes into a weak base under the action of water vapor; the components of Fe2TiO5, Zn, and ZnO in the catalyst are preferably 1:1:1; the metal foam preferably uses titanium metal foam.

[0056] In a preferred embodiment, a steam supply pipe 11 is connected to the feed pipe 4 for inputting steam into the carbon dioxide gas source. When the steam content in the carbon dioxide gas source is low, the steam supply pipe 11 can add steam to the carbon dioxide gas source. An appropriate steam content can not only increase the conductivity of the carbon dioxide gas source but also help create a humid interface required for the electrochemical reaction.

[0057] Specifically preferably, a first analysis indicator 12 is provided on the feed pipe 4 for monitoring the contents of NOx and steam in the carbon dioxide gas source to determine whether the steam content is insufficient. The first analysis indicator 12 is located between the connection of the steam supply pipe 11 and the siphon three-way joint 9.

[0058] Preferably, a second analysis indicator 13 is provided on the discharge pipe 5 for monitoring the contents of NOx and steam in the output gas to monitor whether the remaining amount of NOx in the output gas can meet the standard of food-grade carbon dioxide. Additionally, when the second analysis indicator 13 monitors that the remaining amount of NOx in the output gas reaches a certain value, it can also control the exchange of the oxidation reaction and the reduction reaction in the first tower body 1 and the second tower body 2 to avoid the situation of insufficient remaining reduction gas.

[0059] Preferably, a pressure indicator 14 and a temperature indicator 15 are also provided on the feed pipe 4 for monitoring the pressure and temperature of the carbon dioxide gas source respectively.

[0060] Preferably, differential pressure gauges 16 are provided on both the first tower body 1 and the second tower body 2 for monitoring the pressure difference between the bottom and the top of the first tower body 1 and the second tower body 2 to avoid excessive pressure differences inside the first tower body 1 and the second tower body 2.

[0061] In a preferred embodiment, the oxidation reaction and the reduction reaction in the first tower body 1 and the second tower body 2 are alternated at intervals of a predetermined time. The predetermined time can be comprehensively calculated based on the NOx content in the introduced carbon dioxide gas source, the content of the catalyst in the first tower body 1 / second tower body 2, the content of the reduction gas, and the electrochemical reaction rate, etc., so that the NOx in the carbon dioxide gas source can be fully adsorbed and removed within the predetermined time period.

[0062] Exemplarily, the predetermined time can be 30s to 60s.

[0063] Preferably, the reduction gas is ammonia. Ammonia can react with nitric acid and nitrous acid to produce nitrates and / or nitrites, ammonium salts, and the ammonia generated during the reduction reaction of nitrates and / or nitrites, ammonium salts can also quickly enter and exit the humid interface phase.

[0064] Further, when the reducing gas is ammonia, some ammonium ions will be carried out of the first tower body 1 / second tower body 2 with the output gas due to being dispersed in the gas phase. The discharge pipe 5 is preferably connected with a water washing device and a dehydration device to complete the deammoniation of the output gas.

[0065] Preferably, the first anode plate 101 and the second anode plate 201 are made of titanium alloy material, and the first cathode plate 102 and the second cathode plate 202 are made of magnesium aluminum alloy.

[0066] Preferably, a fifth valve 801 and a sixth valve 802 are arranged on the return pipe 8. The fifth valve 801 and the sixth valve 802 are respectively located on both sides of the discharge pipe 5 to distribute the proportion of the output gas after NOx removal entering the discharge pipe 5 and another tower body.

[0067] It should be noted that the temperature in the first tower body 1 and the second tower body 2 in this system does not exceed 50 °C to avoid the reaction between ammonia and oxygen. And as the catalytic oxidation-reduction reaction proceeds, Zn in the catalyst and the magnesium aluminum alloy of the cathode plate will be gradually consumed, and basic magnesium carbonate will also be gradually and slowly consumed, generating substances such as magnesium nitrate and zinc nitrate. Therefore, it is necessary to replace the conductive catalyst adsorbent and the negative electrode plate in time.

[0068] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for removing NOx from a carbon dioxide gas source for preparing food-grade carbon dioxide, wherein the carbon dioxide gas source contains CO2, NOx, N2, O2, and water vapor, characterized in that: The steps include: S1: introducing a carbon dioxide gas source and excess ammonia into a first reaction chamber and forming a wet interface in the first reaction chamber; NOx undergoes an oxidation reaction in the first reaction chamber and is converted into nitrate and / or nitrite adsorbed on the wet interface, thereby completing the removal of NOx from the carbon dioxide gas source; and introducing the gas from the first reaction chamber after the removal of NOx into a second reaction chamber; S2: A carbon dioxide gas source is input into the second reaction chamber and a wet interface is formed in the second reaction chamber; NOx undergoes an oxidation reaction in the second reaction chamber and is converted into nitrate and / or nitrite adsorbed on the wet interface, thereby completing the removal of NOx by the carbon dioxide gas source, and a portion of the gas after NOx removal in the second reaction chamber is input into the first reaction chamber along the first channel, and a portion is discharged; at the same time, the nitrate and nitrite in the first reaction chamber undergo a reduction reaction to generate ammonia, and the ammonia in the first reaction chamber is input into the second reaction chamber along the second channel to participate in the process of converting NOx into nitrate and / or nitrite; S3: A carbon dioxide gas source is input into the first reaction chamber and a wet interface is formed in the first reaction chamber; NOx undergoes an oxidation reaction in the first reaction chamber and is converted into nitrate and / or nitrite adsorbed on the wet interface, thereby completing the removal of NOx from the carbon dioxide gas source, and a portion of the gas after NOx removal in the first reaction chamber is input into the second reaction chamber along the first channel, and a portion is discharged; at the same time, the nitrate and nitrite in the second reaction chamber undergo a reduction reaction to generate ammonia, and the ammonia in the second reaction chamber is input into the first reaction chamber along the second channel to participate in the process of converting NOx into nitrate and / or nitrite; S4: Repeat steps S2 to S3 until all carbon dioxide gas sources have been completely deNOxed.

2. The method for removing NOx from carbon dioxide gas source according to claim 1, characterized in that: Also includes: The NOx content of the discharged gas after NOx removal is tested to determine whether it meets the standard of food-grade carbon dioxide.

3. The method for removing NOx from carbon dioxide gas source according to claim 1, characterized in that: Also includes: The discharged gas after NOx removal is passed into the water washing and dehydration device for deammoniation treatment.

4. The method for removing NOx from carbon dioxide gas source according to claim 1, characterized in that: Steps S1, S2, and S3 may be performed for a predetermined time period respectively.

5. The method for removing NOx from carbon dioxide gas source according to any one of claims 1 to 4, characterized in that: The oxidation reaction and the reduction reaction are carried out in the following manner: A plurality of first anode plates and a plurality of first cathode plates are arranged alternately in parallel in the first reaction chamber, and a plurality of second anode plates and a plurality of second cathode plates are arranged alternately in parallel in the second reaction chamber. The positive electrode of the power supply is connected to the first anode plate / the second anode plate for oxidation reaction, and the negative electrode of the power supply is connected to the first cathode plate / the second cathode plate for reduction reaction.

6. The method for removing NOx from carbon dioxide gas source according to claim 5, characterized in that: Also includes: Before the carbon dioxide gas source is introduced into the first reaction chamber / the second reaction chamber, electrons are input into the carbon dioxide gas source.

7. The method for removing NOx from carbon dioxide gas source according to claim 5, characterized in that: The moist interface is formed by filling a conductive catalyst adsorbent between adjacent first anode plates and first cathode plates, and filling a conductive catalyst adsorbent between adjacent second anode plates and second cathode plates, wherein the conductive catalyst adsorbent absorbs water vapor in the carbon dioxide gas source to form a moist interface.

8. The method for removing NOx from carbon dioxide gas source according to claim 7, characterized in that: The conductive catalyst adsorbent is composed of basic magnesium carbonate, catalyst components and metal foam, wherein the basic magnesium carbonate is a carrier for absorbing NOx, the catalyst components are composed of Fe2TiO5, Zn and ZnO, and the metal foam is a conductive substrate.

9. The method for removing NOx from carbon dioxide gas source according to claim 7 or 8, characterized in that: Also includes: Before the carbon dioxide gas source is input into the first reaction chamber / the second reaction chamber, the water vapor content of the carbon dioxide gas source is detected. If the water vapor content is insufficient, a certain amount of water vapor is input into the carbon dioxide gas source.

10. The method for removing NOx from carbon dioxide gas source according to claim 5, characterized in that: Conductive catalyst adsorbent is filled between the first anode plate / first cathode plate and the first reaction chamber on both sides; and / or, Conductive catalyst adsorbent is filled between the second anode plate / second cathode plate and the second reaction chamber on both sides.

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