A single-atom fluid-driven carbon dioxide methanation conversion system and its use method

Abstract

The present invention discloses a monatomic fluid driven carbon dioxide methanation conversion system and a method of use, comprising an absorption device and a desorption conversion device, wherein the liquid outlet of the absorption device is connected to the first inlet of a heat exchanger via a first pump, the first outlet of the heat exchanger is connected to the inlet of a desorption conversion device, the liquid outlet of the desorption conversion device is connected to the second inlet of the heat exchanger via a second pump, and the second outlet of the heat exchanger is connected to the liquid inlet of the absorption device via a cooler. The use of monatomic fluid as a solvent in the present invention can not only generate electric charge and effectively solve the problem of high energy consumption caused by desorption of CO2 due to thermal desorption, but also couple thermal and electric charge effects to greatly break through the high energy consumption bottleneck caused by reaction temperature faced by traditional thermal desorption, and greatly reduce the reaction energy barrier and reaction heat. During the desorption process, the charge effect of the molecules in the solvent combined with CO2 can promote the realization of efficient methanation conversion of CO2.

Description

Technical Field

[0001] The present invention relates to the field of process design, and in particular to a monatomic fluid-driven carbon dioxide methanation conversion system and a method of use. Background Art

[0002] Carbon dioxide (CO2), one of the most significant greenhouse gases, has attracted widespread global attention. Currently, my country's CO2 emissions exceed 10 billion tons per year, with energy-intensive industries like electricity, steel, cement, and petrochemicals accounting for over 60% of these emissions. Consequently, my country has proposed a "dual carbon target," setting targets for controlling carbon emissions from energy-intensive industries. CO2 capture and utilization is a key means of achieving this goal.

[0003] Among carbon capture methods, chemical absorption boasts large absorption capacity, good stability, high absorption rate, and low solvent costs. It is considered one of the most mature and closest to industrial application. However, this method's high energy consumption (3.0-5.0 GJ / t CO2) contributes to the high overall cost of CO2 capture, becoming a bottleneck restricting the technology's large-scale industrial application.

[0004] In terms of CO2 utilization, due to the inherent thermodynamic stability and kinetic inertness of CO2, the reaction conditions for its direct conversion into high-value-added chemical products are very harsh and the conversion rate is low, and the yield of the product after the reaction is also low. Currently, most research focuses on the reduction of CO2 by methods such as electrocatalysis and photocatalysis. The core of the method is to design and prepare efficient catalysts to enable the smooth reduction of CO2.

[0005] Industrial carbon dioxide capture technology still lacks a device that can fundamentally address regeneration energy consumption while simultaneously converting CO2 into a resource. A solvent and device that efficiently absorbs CO2 and promotes resource utilization has become a key approach to achieving the "dual carbon goals." A self-propelled carbon dioxide capture system and method are essential to addressing these issues. Summary of the Invention

[0006] In order to overcome the problems of harsh CO2 methanation conversion conditions and low yield in the prior art, the purpose of the present invention is to provide a single-atom fluid driven carbon dioxide methanation conversion system and a method of use.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A monatomic fluid driven carbon dioxide methanation conversion system comprises an absorption device, a desorption conversion device, a heat exchange device and a circulation device, wherein the heat exchange device comprises a heat exchanger and a first cooler; the circulation device comprises a first pump and a second pump; the desorption conversion device is provided with a liquid outlet and a gas outlet;

[0009] A liquid inlet is provided on the upper side wall of the absorption device, a gas inlet is provided on the lower side wall, an exhaust gas outlet is provided at the top, and a liquid outlet is provided at the bottom. The liquid outlet of the absorption device is connected to the first inlet of the heat exchanger through a first pump, the first outlet of the heat exchanger is connected to the inlet of the desorption conversion device, the liquid outlet of the desorption conversion device is connected to the second inlet of the heat exchanger through a second pump, and the second outlet of the heat exchanger is connected to the liquid inlet of the absorption device through a first cooler.

[0010] Furthermore, a first liquid level gauge is provided in the absorption device.

[0011] Furthermore, the heat exchanger is a tubular heat exchanger or a plate heat exchanger.

[0012] Furthermore, the desorption conversion device is provided with a magnetic stirring device, a pressure gauge, a second liquid level gauge and a temperature detector.

[0013] Furthermore, a jacket for heating is provided on the outside of the desorption conversion device, heat transfer oil is provided in the jacket, and the desorption conversion device is connected to a nitrogen bottle.

[0014] Furthermore, a first flow meter is provided between the second pump and the heat exchanger, and a second flow meter is provided between the first outlet of the heat exchanger and the desorption conversion device.

[0015] Furthermore, the first flowmeter and the second flowmeter are turbine flowmeters.

[0016] Furthermore, the gas outlet of the desorption conversion device is connected to a methane storage tank via a second cooler and a compressor.

[0017] A method for using the above-mentioned monatomic fluid-driven carbon dioxide methanation conversion system comprises the following steps:

[0018] 1) Adding a monatomic fluid to an absorption device and passing carbon dioxide-rich industrial flue gas into the absorption device, with the monatomic fluid flowing from top to bottom and the carbon dioxide-rich industrial flue gas flowing from bottom to top. The monatomic fluid and the carbon dioxide-rich industrial flue gas react, allowing the carbon dioxide in the industrial flue gas to fully dissolve in the monatomic fluid, forming a carbon dioxide-rich monatomic fluid;

[0019] 2) The carbon dioxide-rich monatomic fluid is transported to a desorption conversion device through a first pump and a heat exchanger. The carbon dioxide-rich monatomic fluid desorbs carbon dioxide, generating electric charges during the temperature change of the monatomic fluid solvent. The electric charges catalyze water in the monatomic fluid solvent to electrolyze and produce hydrogen. The hydrogen and carbon dioxide are then catalytically converted into methane under the drive of the electric charges of the monatomic fluid.

[0020] Furthermore, the monatomic fluid after desorbing carbon dioxide in the desorption conversion device is transported to the absorption device after passing through a heat exchanger;

[0021] The monatomic fluid reacts with industrial flue gas rich in carbon dioxide at 20-40°C and 0.1 MPa;

[0022] The carbon dioxide-rich monatomic fluid desorbs carbon dioxide at a temperature of 140-160°C and a pressure of 1.7-1.9 MPa.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The carbon dioxide methanation system driven by a single atomic fluid in this invention is a new green system that integrates carbon dioxide capture and resource utilization. It has the following two major advantages: First, the integrated single atomic fluid desorption and conversion device proposed in this invention solves the problem of high energy consumption caused by thermal desorption, which is a limitation of traditional carbon dioxide capture processes. Compared with the traditional chemical absorption method (which relies solely on high-pressure steam to desorb CO2 and consumes more than 3.5GJ / tCO2), the highly stable single atomic fluid proposed in this invention effectively overcomes the cognitive blind spot that metal atoms and solvents cannot coexist through atomic competition and thermoelectric effects. By coupling thermal and charge effects, it greatly overcomes the reaction bottleneck of traditional thermal desorption, significantly reduces the reaction energy barrier and reaction heat, breaks the bottleneck of the development of low-temperature reactions from high-temperature reactions, significantly reduces the reaction temperature, and fundamentally solves the energy consumption bottleneck of traditional chemical absorption methods. Second, it matches the thermoelectric effect of the carbon capture and desorption process with the heat and mass transfer of the carbon dioxide methanation reaction. The reaction of monatomic fluid with carbon dioxide has the characteristics of high charge production, low heat and mass transfer resistance, and energy storage (high thermal storage density). Compared with the traditional carbon dioxide methanation conditions (275-375℃, 3-5MPa), the reaction conditions are milder and the energy consumption is greatly reduced. At the same time, CO2 can be converted into resources to produce methane products with economic value.

[0025] The present invention utilizes a monatomic fluid as a solvent. This novel capture solvent exhibits a strong thermoelectric effect, generating electric charge, effectively resolving the energy consumption bottleneck of CO2 desorption, which is often limited by thermal desorption. Furthermore, the coupling of thermal and electric charge effects significantly overcomes the high energy consumption bottleneck of traditional thermal desorption, resulting from the high reaction temperature, significantly reducing the reaction energy barrier and heat. Furthermore, the charge interaction between the molecules in the solvent and the CO2 during the desorption process promotes efficient methanation of CO2, replacing traditional high-temperature methanation reactions with lower energy consumption and achieving CO2 conversion under relatively mild reaction conditions, thus possessing significant scientific and application value.

[0026] Furthermore, the present invention, driven by a single-atom fluid, enables the methanation of carbon dioxide under mild conditions of 160°C and 1.8 MPa, producing methane product gas with a maximum purity of 60% (volume fraction). This system boasts a simple structure, easy operation, and no hazardous waste. It also facilitates the reduction of greenhouse gas carbon dioxide emissions and its efficient resource conversion, effectively addressing greenhouse gas emissions and, in the long term, alleviating my country's energy shortages, which are characterized by abundant coal, poor oil, and limited natural gas resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the process flow diagram of the single-atom fluid-driven carbon dioxide methanation conversion system.

[0028] In the figure, 1 is an absorption device, 2 is a first liquid level gauge, 3 is a first pump, 4 is a first valve, 5 is a first flow meter, 6 is a second valve, 7 is a second pump, 8 is a heat exchanger, 9 is a first cooler, 10 is a second flow meter, 11 is a third valve, 12 is a desorption conversion device, 13 is a second cooler, 14 is a methane storage tank, 15 is a magnetic stirring device, 16 is a pressure gauge, 17 is a second liquid level gauge, 18 is a jacket, 19 is a nitrogen cylinder, 20 is a pressure reducing valve, 21 is a compressor, 22 is a fourth valve, and 23 is a temperature detector. DETAILED DESCRIPTION

[0029] The present invention is described in detail below.

[0030] See also Figure 1 The present invention relates to a monatomic fluid-driven carbon dioxide methanation conversion system, which mainly includes four devices, namely an absorption device, a desorption conversion device, a heat exchange device and a circulation device. The heat exchange device includes a heat exchanger 8 and a first cooler 9. The circulation device includes a first pump 3, a first valve 4, a first flowmeter 5, a second valve 6 and a second pump 7. The power of the circulation device comes from the first pump 3 and the second pump 7. The first pump 3 and the second pump 7 are fluoroplastic corrosion-resistant pumps. The head of the first pump 3 and the second pump 7 meets the head requirements of the two liquids in the circulation device circulating to the corresponding devices.

[0031] A first liquid level gauge 2 is provided in the absorption device 1 .

[0032] Two liquid inlets are provided on the upper side wall of the absorption device 1, a gas inlet is provided on the lower side wall, an exhaust gas outlet is provided at the top, and a liquid outlet is provided at the bottom. The liquid outlet of the absorption device 1 is connected to the first inlet of the heat exchanger 8 through the first pump 3 and the first valve 4. The first outlet of the heat exchanger 8 is connected to the inlet of the desorption conversion device 12 through the second flowmeter 10 and the third valve 11. The gas outlet of the desorption conversion device 12 is connected to the methane storage tank 14 through the second cooler 13 and the compressor 21.

[0033] The heat exchanger 8 can be a tubular heat exchanger or a plate heat exchanger.

[0034] The desorption / conversion device 12 is equipped with a magnetic stirring device 15, a pressure gauge 16, a second liquid level gauge 17, and a temperature detector 23. The pressure gauge 16 is used to monitor the pressure within the desorption / conversion device 12. The temperature detector 23 is a temperature probe. The magnetic stirring device 15 can accelerate the conversion reaction rate.

[0035] The desorption / conversion device 12 can be heated by an oil bath (using dimethyl silicone oil as the heat transfer oil), external wall coil heating, or jacket heating. Preferably, a jacket 18 is provided externally for heating, containing heat transfer oil (dimethyl silicone oil). The desorption / conversion device 12 is connected to a nitrogen cylinder 19, and a pressure reducing valve 20 is provided between the desorption / conversion device 12 and the nitrogen cylinder 19.

[0036] The liquid outlet of the desorption conversion device 12 is connected to the second inlet of the heat exchanger 8 through the second pump 7 and the first flowmeter 5. The second outlet of the heat exchanger 8 is connected to a liquid inlet of the absorption device 1 through the first cooler 9 and the fourth valve 22.

[0037] The first flow meter 5 and the second flow meter 10 are turbine flow meters for monitoring flow rates.

[0038] The absorption device is the place where industrial flue gas rich in carbon dioxide reacts with the monatomic fluid solvent. The solvent flows from top to bottom, fully contacts and reacts with the industrial flue gas from bottom to top, and fully reacts under the conditions of 20-40°C and 0.1MPa, so that the carbon dioxide in the industrial flue gas is fully dissolved in the monatomic fluid solvent, that is, the monatomic fluid solvent can absorb the carbon dioxide in the industrial flue gas. The monatomic fluid solvent rich in carbon dioxide enters the desorption conversion device 12 after heat exchange and temperature increase in the heat exchange device under the action of the delivery pump (first pump 3 and second pump 7) of the circulation device.

[0039] In desorption conversion unit 12, post-absorption solvent desorption and post-desorption CO2 conversion processes are carried out. Specifically, the CO2-rich monatomic fluid solvent desorbs CO2 at a temperature of 140-160°C and a pressure of 1.7-1.9 MPa, and is then driven by the monatomic fluid to convert CO2 into methane. After conversion, regenerated monatomic fluid solvent and methane product are obtained. The newly generated monatomic fluid solvent is reused in absorption unit 1, and the methane product is transported out of the system.

[0040] The circulation system includes two loops, namely, the monatomic fluid solvent separated by the desorption conversion device 12 is circulated to the absorption device 1 for reuse, and the monatomic fluid solvent absorbed by CO2 in the absorption device 1 is circulated to the desorption conversion device 12.

[0041] The circulation device provides power for the flow of the monatomic fluid solvent in the absorption device 1 and the desorption conversion device 12, is the catalytic driving force of the conversion reaction, and replenishes the monatomic fluid solvent to the absorption device 1 in time.

[0042] The heat exchange system includes two loops, one for exchanging heat between the monatomic fluid solvent (high temperature) separated by the desorption conversion device 12 and the other for exchanging heat between the monatomic fluid solvent (low temperature) that has absorbed carbon dioxide in the absorption device 1. After the heat exchange, the monatomic fluid solvent separated by the desorption conversion device 12 is further cooled by cooling water to a specified temperature and then enters the absorption device 1.

[0043] Since the monatomic fluid solvent after desorption and conversion contains a large amount of heat, it can provide part of the heat for the solvent that absorbs carbon dioxide. After being cooled again and reaching the reaction temperature of the absorption device 1, it enters the device for recycling.

[0044] The method of use of the present invention comprises the following steps:

[0045] 1) A monatomic fluid is added as a solvent into the absorption device 1 from a liquid inlet of the absorption device 1, and industrial flue gas rich in carbon dioxide is introduced from the gas inlet of the absorption device 1. The solvent flows from top to bottom, and the industrial flue gas rich in carbon dioxide flows from bottom to top. The solvent and the industrial flue gas rich in carbon dioxide are fully contacted and reacted under the conditions of 20-40° C. and 0.1 MPa, so that the carbon dioxide in the industrial flue gas is fully dissolved in the monatomic fluid solvent to form a monatomic fluid solvent rich in carbon dioxide; and the purified tail gas is discharged.

[0046] Among them, the monatomic fluid is mainly composed of formamide, copper hydride and other components. After obtaining the monatomic fluid, it is fully mixed with alcoholamine and water under magnetic stirring to obtain a monatomic fluid solvent (for the detailed composition and preparation method of the monatomic fluid, please refer to the patent "A preparation method of monatomic fluid containing metallic copper 202110809035.X").

[0047] The monatomic fluid solvent acts as a catalytic substance for the methanation of carbon dioxide. After absorbing carbon dioxide in the absorption device 1, it releases carbon dioxide in the desorption conversion device 12 and promotes its conversion into methane products, thereby completing the process of carbon dioxide capture and resource utilization.

[0048] 2) The carbon dioxide-rich monatomic fluid is transported to the desorption conversion device 12 through the first pump 3, the first valve 4, the heat exchanger 8, the second flowmeter 10, and the third valve 11. The carbon dioxide-rich monatomic fluid solvent desorbs carbon dioxide at a temperature of 140-160°C and a pressure of 1.7-1.9 MPa. Under the action of the electric charge generated during the heating and cooling process of the monatomic fluid solvent, water in the catalytic system is first electrolyzed to produce hydrogen. The hydrogen and carbon dioxide are then catalytically converted into methane under the drive of the electric charge of the monatomic solvent. After passing through the desorption conversion device 12, a methane product with a purity of approximately 60% (volume fraction) and a small amount of hydrogen can be obtained.

[0049] The pressure condition of 1.7-1.9 MPa is achieved by introducing nitrogen into the desorption conversion device 12.

[0050] 3) Methane is transported to methane storage tank 14 via second cooler 13 and compressor 21. The desorbed carbon dioxide monatomic fluid is transported to absorption device 1 via second pump 7, second valve 6, first flowmeter 5, heat exchanger 8, first cooler, and fourth valve 22.

[0051] The high-temperature monatomic fluid solvent (about 140-160°C) after the desorption reaction from the desorption conversion device 12 and the low-temperature monatomic fluid solvent containing carbon dioxide (about 30-40°C) from the absorption device 1 are heat exchanged in the heat exchanger 8.

[0052] Example 1

[0053] The flue gas containing carbon dioxide is introduced into the absorption device. After being absorbed by the monatomic fluid solvent, 60 ml of the monatomic fluid solvent rich in carbon dioxide is obtained and sent to the desorption conversion device 12 through the delivery pumps (first pump 3 and second pump 7) of the circulation device. The desorption conversion device 12 is pressurized with nitrogen to reach a pressure of 1.8 MPa. The temperature in the desorption conversion device 12 reaches 160°C in a dimethyl silicone oil bath. Under the action of magnetic stirring, after sufficient reaction, the methane content in the product gas is measured by a gas detector to be 60%, and the carbon dioxide content is 4.6% (volume fraction).

[0054] Example 2

[0055] The flue gas containing carbon dioxide is introduced into the absorption device 1. After absorption by the monatomic fluid solvent, 60 ml of monatomic fluid solvent rich in carbon dioxide is obtained and sent to the desorption conversion device 12 through the delivery pumps (first pump 3 and second pump 7) of the circulation device. Nitrogen is used to pressurize the desorption conversion device 12 to reach a pressure of 1.9 MPa. The desorption conversion device 12 is heated to 155°C in a dimethyl silicone oil bath. Under the action of magnetic stirring, after sufficient reaction, the methane content in the product gas is measured by a gas detector to be 49%, and the carbon dioxide content is 6.5% (volume fraction).

[0056] The advantages of the present invention are as follows: the present invention uses a monatomic fluid as a solvent as a capture solvent for carbon dioxide, and realizes monatomic fluid-driven carbon dioxide methanation through the four devices of the absorption device 1, the desorption conversion device 12, the heat exchange device and the circulation device. The monatomic fluid solvent of the absorption device 1 and the desorption conversion device 12 is recycled by the circulation device, so that the solvent is fully utilized in the system, saving operating costs and waste liquid treatment costs, and solving the problems of harsh reaction conditions and low yields of industrial carbon dioxide methanation. The system is easy to operate and has low operating and maintenance costs. At the same time, it can realize the resource utilization of greenhouse gases. Its promotion and use can help my country achieve the "dual carbon" goal as soon as possible and provide a feasible way for the resource utilization of carbon dioxide.

Claims

1. A monatomic fluid driven carbon dioxide methanation conversion system, characterized in that: The invention comprises an absorption device (1), a desorption conversion device (12), a heat exchange device and a circulation device, wherein the heat exchange device comprises a heat exchanger (8) and a first cooler (9); the circulation device comprises a first pump (3) and a second pump (7); and the desorption conversion device (12) is provided with a liquid outlet and a gas outlet. The absorption device (1) is provided with a liquid inlet on the upper side wall, a gas inlet on the lower side wall, a tail gas outlet at the top, and a liquid outlet at the bottom. The liquid outlet of the absorption device (1) is connected to the first inlet of the heat exchanger (8) via the first pump (3), the first outlet of the heat exchanger (8) is connected to the inlet of the desorption conversion device (12), the liquid outlet of the desorption conversion device (12) is connected to the second inlet of the heat exchanger (8) via the second pump (7), and the second outlet of the heat exchanger (8) is connected to the liquid inlet of the absorption device (1) via the first cooler (9); The desorption conversion device (12) is provided with a magnetic stirring device (15), a pressure gauge (16), a second liquid level gauge (17) and a temperature detector (23); A jacket (18) for heating is provided outside the desorption conversion device (12), and heat-conducting oil is provided inside the jacket (18). The desorption conversion device (12) is connected to a nitrogen bottle (19).

2. The monatomic fluid driven carbon dioxide methanation conversion system according to claim 1, characterized in that: A first liquid level gauge (2) is provided in the absorption device.

3. The monatomic fluid driven carbon dioxide methanation conversion system according to claim 1, characterized in that: The heat exchanger (8) is a tube type heat exchanger or a plate type heat exchanger.

4. The monatomic fluid driven carbon dioxide methanation conversion system according to claim 1, characterized in that: A first flow meter (5) is provided between the second pump (7) and the heat exchanger (8), and a second flow meter (10) is provided between the first outlet of the heat exchanger (8) and the desorption conversion device (12).

5. The monatomic fluid driven carbon dioxide methanation conversion system according to claim 4, characterized in that: The first flow meter (5) and the second flow meter (10) are turbine flow meters.

6. The monatomic fluid driven carbon dioxide methanation conversion system according to claim 1, characterized in that: The gas outlet of the desorption conversion device (12) is connected to a methane storage tank (14) via a second cooler (13) and a compressor (21).

7. A method for using the monatomic fluid driven carbon dioxide methanation conversion system according to any one of claims 1 to 6, characterized in that: The following steps are involved: 1) adding a monatomic fluid into an absorption device (1), passing industrial flue gas rich in carbon dioxide into the absorption device (1), wherein the monatomic fluid flows from top to bottom, and the industrial flue gas rich in carbon dioxide flows from bottom to top, and the monatomic fluid reacts with the industrial flue gas rich in carbon dioxide, so that the carbon dioxide in the industrial flue gas is fully dissolved in the monatomic fluid, thereby forming a monatomic fluid rich in carbon dioxide; 2) The carbon dioxide-rich monatomic fluid is transported from the first pump (3) and the heat exchanger (8) to the desorption conversion device (12). The carbon dioxide-rich monatomic fluid desorbs carbon dioxide, and generates electric charges during the temperature change of the monatomic fluid solvent. The electric charges catalyze water in the monatomic fluid solvent to electrolyze and generate hydrogen, and the hydrogen and carbon dioxide are catalytically converted into methane under the drive of the electric charges of the monatomic fluid.

8. A method of use according to claim 7, characterized in that: The monatomic fluid after carbon dioxide is desorbed from the desorption conversion device (12) is transported to the absorption device (1) after passing through the heat exchanger (8); The monatomic fluid reacts with industrial flue gas rich in carbon dioxide at 20-40°C and 0.1 MPa; The carbon dioxide-rich monatomic fluid desorbs carbon dioxide at a temperature of 140-160°C and a pressure of 1.7-1.9 MPa.

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