CO2-containing gas concentration method and application

Abstract

The invention relates to the technical field of CO2 concentration processes, in particular to a CO2-containing gas concentration method which comprises the steps that CO2-containing gas is oxidized or combusted, high-concentration CO2 is obtained, and the CO2 concentration in the oxidized or combusted high-concentration CO2 is larger than 90%. According to the invention, CO2-containing gas is used as combustion-supporting gas instead of air, and is introduced into a coal-fired boiler or a natural gas boiler for combustion reaction. O2 in the product gas is converted into CO2 after combustion, high-concentration product gas with the CO2 concentration of 94%-97% is obtained, and the CO2 with the concentration can be directly used for oil displacement or sealing treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of CO2 concentration process, and particularly relates to a CO2-containing gas concentration method and application. BACKGROUND

[0002] Carbon capture and storage technology (CCS) can capture carbon dioxide in emission sources, and is one of the main measures for large-scale carbon dioxide emission reduction. Carbon capture is a key technology for carbon reduction. In the field of carbon capture, the organic amine absorption method will occupy an important position in the next 20 years. However, the energy consumption of the regeneration process of the current organic amine is high, and the economic cost is high. It is necessary to develop a new capture process with low energy consumption and low cost. Based on the coupling of carbon capture, green hydrogen, green ammonia and green methanol conversion technology, the regeneration of absorbent is combined with the electrolysis of water to produce hydrogen, so as to reduce the total cost. However, in addition to the parameter CO2, about 29wt% O2 will also be produced at the anode. Therefore, the product gas CO2 needs to be concentrated. The current CO2 or oxygen separation technologies are as follows:

[0003] The authorized invention patent of Chinese patent application number "CN202222799816" discloses "an air oxygen element collection device capable of quickly separating nitrogen elements". The invention provides a nitrogen-oxygen separation technology by pressure swing adsorption. The application patent of Chinese patent number "CN201610405254.0" discloses "a non-aqueous solvent carbon dioxide capture liquid, method and system". The invention provides a solvent method for capturing carbon dioxide.

[0004] At present, low-cost nitrogen-oxygen separation and low-cost carbon-nitrogen separation are widely studied, but the following main challenges still exist:

[0005] (1) It is difficult to separate CO2 and O2 by pressure swing adsorption due to the similar kinetic volumes of CO2 and O2.

[0006] (2) O2 has an oxidation effect on the CO2 absorbent, which shortens the service life of the absorbent.

[0007] In order to avoid the above two problems existing in the separation of CO2 and O2, the mainstream technical solution adopts cooling liquefaction separation or low-temperature methanol washing. However, the following challenges still exist: (1) The cost of small-scale cooling liquefaction separation is too high, and a large amount of oxygen entering the market will cause a huge fluctuation in the price of oxygen, affecting economic benefits; (2) The mixture of methanol vapor and oxygen is an explosive gas on site, and the safety risk is huge. SUMMARY

[0008] The application aims to provide a method for concentrating CO2-containing gas and application, which replaces air with product gas (70% CO2, 26% O2, 4% H2O) obtained by electrolytic regeneration as combustion-supporting gas, and then the product gas is introduced into a coal-fired boiler or a natural gas boiler to perform a combustion reaction. O2 in the product gas is converted into CO2 after combustion, and high-concentration product gas with a CO2 concentration of 94%-97% is obtained, and the high-concentration CO2 can be directly used for oil displacement or storage treatment. In order to achieve the above-mentioned purpose, the application provides the following technical solutions:

[0009] The application provides a method for concentrating CO2-containing gas, which comprises,

[0010] The CO2-containing gas is oxidized or combusted to obtain high-concentration CO2, wherein,

[0011] The CO2 concentration in the high-concentration CO2 is greater than 90%.

[0012] Further, the CO2-containing gas comprises CO2 and O2.

[0013] The CO2 concentration is less than or equal to 90%, and the O2 concentration is greater than 10%.

[0014] Further, the CO2-containing gas comprises CO2, O2 and H2O.

[0015] The CO2 concentration is less than or equal to 76%, the O2 concentration is greater than 20%, and the H2O concentration is less than or equal to 4%.

[0016] Further, the CO2-containing gas is oxidized or combusted.

[0017] O2 in the CO2-containing gas is converted into CO2 after combustion.

[0018] Further, the method further comprises,

[0019] The high-concentration CO2 is recovered or stored.

[0020] Further, the method comprises,

[0021] The CO2-containing gas is introduced into a coal-fired boiler to perform oxidation or combustion, and high-concentration CO2 is obtained.

[0022] Further, the method comprises,

[0023] The CO2-containing gas is introduced into a natural gas boiler to perform oxidation or combustion, and high-concentration CO2 is obtained.

[0024] Further, the method comprises,

[0025] The CO2-containing gas is introduced into a natural gas boiler or an electric oxidation device to be oxidized to obtain high-concentration CO2.

[0026] The application of the high-concentration CO2 obtained by the method for concentrating CO2-containing gas as described above in oil displacement.

[0027] Technical effects and advantages of the present application:

[0028] The energy-consuming process is changed into an energy-generating process by the method, the method is simple and easy to operate, and the operation cost is effectively reduced. In addition, the process can increase the processing scale of carbon capture by 20-30%.

[0029] Other features and advantages of the present application will be described in the following description, and some will become apparent from the description, or will be understood by those skilled in the art. The purpose and other advantages of the present application can be achieved and obtained by the structure indicated in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 Concentration diagram of CO2-containing gas obtained by the electrochemical regeneration method in the specific embodiments of the present application. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0032] To solve the problems in the prior art, the present application discloses a method for concentrating CO2-containing gas, which comprises: introducing CO2-containing gas instead of air as combustion-supporting gas to be oxidized or combusted, converting O2 in the product gas into CO2 after combustion to obtain high-concentration CO2, and recovering or storing the high-concentration CO2.

[0033] In some specific embodiments of the present application, the CO2 concentration in the high-concentration CO2 after oxidation or combustion is greater than 90%, and the obtained high-concentration CO2 can be used for oil displacement.

[0034] In some specific embodiments of the present application, the CO2-containing gas comprises CO2 and O2, wherein the CO2 concentration is less than or equal to 80%, and the O2 concentration is greater than 20%.

[0035] In some specific embodiments of the present invention, the CO2-containing gas includes CO2, O2 and H2O; wherein the CO2 concentration is less than or equal to 70%, the O2 concentration is greater than 26%, and the H2O concentration is less than or equal to 4%.

[0036] In some specific embodiments of the present invention, CO2-containing gas is introduced into a coal-fired boiler for oxidation or combustion to obtain high-concentration CO2.

[0037] In some specific embodiments of the present invention, CO2-containing gas is introduced into a natural gas boiler for oxidation or combustion to obtain high-concentration CO2.

[0038] In some specific embodiments of the present invention, the CO2-containing gas is a product gas obtained by electrolytic regeneration.

[0039] This method transforms an energy-consuming process into a productive one, effectively reducing operating costs. Furthermore, the process can increase the scale of carbon capture by 20%-30%.

[0040] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0041] Example 1

[0042] like Figure 1 As shown, electrochemical regeneration is used to obtain CO2-containing gas at the electrode, where the CO2 product gas has an oxygen concentration of 26%, a CO2 concentration of 70%, an O2 concentration of 26%, and a H2O concentration of 4%. The O2 concentration in this product is too high, and the CO2 concentration is too low (less than 90%) to be directly injected or used in subsequent chemical processes. This product gas is then fed into the boiler as a combustion-supporting gas (O2 source) instead of air for a combustion reaction. After combustion, the O2 is converted into CO2, resulting in a high-concentration CO2, with a CO2 concentration of 97%.

[0043] Example 2

[0044] The electrochemical reactor has a CO2 mass flow rate of 1.25 tons / hour and produces an oxygen mass flow rate of 0.45 tons / hour. The anode gas is a mixed gas with an O2 concentration of 30% and a CO2 concentration of 70%. This anode gas (containing CO2 gas) is used instead of air to pass into a coal-fired boiler or a gas-fired boiler. After combustion in the boiler, the outlet gas has an O2 concentration of 5% and a CO2 concentration of 95%, and the gas mass flow rate increases to 1.72 tons / hour. Using this technology, the CO2 concentration can be increased from 70% to 95%, and the CO2 flow rate increases by 30%. Since high-concentration CO2 can be used for direct oil recovery or storage, the carbon capture of this process increases by 30%, and the unit carbon capture cost decreases by 23%.

[0045] Example 3

[0046] 10000Nm 3 / hour, and the tail gas is a mixed gas with N2 concentration of 80%, O2 concentration of 5%, and CO2 concentration of 15%. After the air separation treatment by nitrogen, the tail gas flow is 2000Nm 3 / hour, and the components are O2 concentration of 25% and CO2 concentration of 75%. The anode gas (CO2-containing gas) is used to replace air to be introduced into a coal-fired boiler or a gas-fired boiler, and after the combustion of the boiler, the outlet gas has O2 concentration of 5% and CO2 concentration of 95%. By using the technology, the CO2 concentration can be increased from 15% to 95%, and the CO2 flow is increased by 1900Nm 3 / hour. 3 / hour. Since the high-concentration CO2 can be directly used for oil displacement or storage, the carbon capture of the process is increased by 25%, and the unit carbon capture cost is reduced by 20%.

[0047] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or equivalently replace some technical features, as long as they are within the spirit and principles of the present application. Any modification, equivalent replacement, improvement, etc. should be included in the protection scope of the present application.

Claims

1. A method for concentrating a CO2-containing gas, characterized by, The method comprises, oxidizing or combusting the CO2-containing gas to obtain high-concentration CO2, wherein, the CO2 concentration in the high-concentration CO2 after oxidation or combustion is greater than 90%.

2. A method of concentrating a CO2-containing gas according to claim 1, characterized by, The CO2-containing gas also contains O2. The CO2 concentration is less than or equal to 90%, and the O2 concentration is greater than 10%.

3. The method of claim 1, wherein the CO2-containing gas is a flue gas. The CO2-containing gas contains O2 and H2O. The CO2 concentration is less than or equal to 76%, the O2 concentration is greater than 20%, and the H2O concentration is less than or equal to 4%.

4. The method of claim 1, wherein the CO2-containing gas is a flue gas. The CO2-containing gas is oxidized or combusted; O2 in the CO2-containing gas is converted into CO2 after combustion.

5. The method of claim 1, wherein the CO2-containing gas is a flue gas. The method further comprises, recovering or sequestering the high-concentration CO2.

6. The method of claim 1, wherein the CO2-containing gas is a flue gas. The method comprises, feeding the CO2-containing gas into a coal-fired boiler to oxidize or combust the gas and obtain high-concentration CO2.

7. The method of claim 1, wherein the CO2-containing gas is a flue gas. The method comprises, feeding the CO2-containing gas into a natural gas boiler to oxidize or combust the gas and obtain high-concentration CO2.

8. The method of claim 1, wherein the CO2-containing gas is a flue gas. The method further comprises, feeding the CO2-containing gas into an electro-oxidation device to oxidize or combust the gas and obtain high-concentration CO2.

9. The method for concentrating CO2-containing gas according to any one of claims 1-8, wherein, the CO2-containing gas is product gas obtained by electrolytic regeneration and flue gas.

10. Use of high-concentration CO2 obtained by the method for concentrating CO2-containing gas according to any one of claims 1-9 in oil displacement.

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