Carbon sequestration equipment for carbon dioxide
By designing a carbon device that contains temperature -controlled devices, integrates methane reactions and thermal cracking reactions, solves the problem of reaction temperature differences and catalytic losses in existing technologies, and realizes efficient carbon dioxide carbon fixation.
Patent Information
- Application Number
- CN202310888892.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-19
- Publication Date
- 2025-01-21
AI Technical Summary
In the existing carbon dioxide carbon sequestration technology, the methanation reaction of carbon dioxide and the thermal cracking reaction of methane are difficult to integrate the corresponding device due to the difference in reaction temperature, and the catalyst of the methanation reaction device is prone to deactivate.
Design a solid carbon device including methane reaction device, temperature control device, methane thermal cracking device and stove. The temperature of the methane reaction and thermal crack reaction reaction through the temperature control device is controlled to the suitable range to avoid directly transmitting heat to methane to methane directly to methane Reaction device to protect the catalyst activity.
The integration of methane reaction device and methane thermal cracking device, saving space needs, and avoiding the problem of catalyst loss, improving the carbon fixed efficiency of carbon dioxide.
Smart Images
Figure CN119327369A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a carbon dioxide fixation device. Background Art
[0002] Carbon dioxide is a greenhouse gas that is the main culprit of climate change. In recent years, under the influence of carbon emission policies, countries around the world have been working hard to reduce carbon dioxide emissions. In addition to reducing carbon dioxide emissions, there are also related technologies that are being studied to convert emitted carbon dioxide into solid carbon.
[0003] Furthermore, due to the large carbon-oxygen bond energy of carbon dioxide (799KJ / mol), carbon dioxide has a relatively stable chemical property under general conditions, making it difficult to directly fix carbon. Specifically, the energy required for the direct reduction of carbon dioxide to form solid carbon is large, and the catalyst is easily sintered and deactivated under high temperature conditions. Therefore, there has always been a technical bottleneck in converting carbon dioxide into solid carbon by a single-pass reaction.
[0004] Therefore, in order to break through the above bottleneck, a two-stage carbon dioxide fixation method has been proposed. Specifically, the two-stage carbon fixation method is to first convert carbon dioxide into methane, and then thermally crack the methane to convert it into solid carbon and hydrogen. Therefore, it has the advantage of easy process operation.
[0005] However, in the two-stage carbon fixation method, the methanation reaction of carbon dioxide and the thermal cracking reaction of methane are carried out, so a methanation reaction device and a methane thermal cracking device must be used. That is, when the two-stage carbon fixation method is carried out in an industrial production mode (such as a continuous reaction), the space requirement for placing the reaction equipment is increased compared to the single-pass reaction. Summary of the invention
[0006] Next, generally speaking, the methanation reaction of carbon dioxide (CO2+4H2→CH4+2H2O) is carried out at a reaction temperature of 200-500°C, while the thermal cracking reaction of methane (CH4→C+2H2) is carried out at a reaction temperature of 600-1100°C. The reaction temperatures of the two do not overlap, so there is a difference in reaction temperature. In addition, based on this difference in reaction temperature, there is a problem that it is difficult to integrate the methanation reaction device and the methane thermal cracking device into the same equipment.
[0007] In addition, because different catalysts may be used in the methanation reaction of carbon dioxide and the thermal cracking reaction of methane, and the catalysts generally used in the methanation reaction have a lower upper limit of the temperature range in which they are active, based on the above-mentioned difference in reaction temperature, if the heat from the methane thermal cracking unit is directly transferred to the methanation reaction unit, the problem of catalyst deactivation in the methanation reaction unit may arise.
[0008] In order to solve the above problems, a carbon dioxide fixation device according to an embodiment of the present invention comprises: a methanation reaction device, which reacts carbon dioxide with hydrogen and converts it into methane; a temperature control device, which comprises a tube layer and a shell layer surrounding the tube layer; a methane thermal cracking device, which thermally cracks methane into solid carbon and hydrogen; and a furnace; wherein, in the carbon fixation device, the methanation reaction device, the temperature control device, the methane thermal cracking device and the furnace are connected to each other in this order.
[0009] In an embodiment, the carbon fixation equipment is a concentric circle structure.
[0010] In an embodiment, the tube layer is a spiral tube wound in multiple turns.
[0011] In an embodiment, the tube layer includes a spiral tube near the inlet of the methanation reaction device and a spiral tube near the outlet of the methanation reaction device, and the ratio of the number of turns of the spiral tube near the inlet of the methanation reaction device to the number of turns of the spiral tube near the outlet of the methanation reaction device is 1.5:1 to 3:1.
[0012] In an embodiment, the carbon fixation equipment further comprises: a heat exchanger connected to the methanation reaction device and cooling the product from the methanation reaction device; and a water cooling device connected to the heat exchanger and removing water from the cooled product.
[0013] In an embodiment, the source of hydrogen in the methanation reaction device is hydrogen produced by a water electrolysis device or the methane thermal cracking device.
[0014] In an embodiment, the heat source in the methane thermal cracking device is the combustion heat from the furnace or external waste heat.
[0015] In an embodiment, the cracked gas produced by the methane thermal cracking unit is burned back to provide heat to the furnace.
[0016] In an embodiment, the tube layer flows water and the shell layer flows methanogenic synthesis gas.
[0017] In an embodiment, the flow rate of the water is 50-1500 ml / h.
[0018] In view of the above existing problems, the present invention provides a carbon fixation device for carbon dioxide, which integrates a methanation reaction device and a methane thermal cracking device through a temperature control device to save space for placing the reaction device and can easily operate the carbon fixation of the gas containing carbon dioxide. Furthermore, the problem of catalyst deactivation in the methanation reaction device can also be avoided. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1It is a schematic diagram of a carbon dioxide fixation device according to a first embodiment of the present invention.
[0020] Figure 2 FIG. 1 is a schematic diagram of a carbon dioxide fixation device according to a second embodiment of the present invention.
[0021] Figure 3 It is a schematic diagram of a carbon dioxide fixation device according to a third embodiment of the present invention.
[0022] Figure 4 Schematic diagram of the temperature control device of the present invention.
[0023] Figure 5 Schematic diagram of the tube layer of the present invention.
[0024] Reference numerals
[0025] 1 Methanation reaction unit
[0026] 2 Temperature control device
[0027] 21 Tube layer
[0028] 21a Spiral pipe near the inlet of methanation reaction unit
[0029] 21b Spiral pipe near the outlet of methanation reaction device
[0030] 211 Tube Layer Entrance
[0031] 22 Shell
[0032] 221 Shell Entrance
[0033] 3 Methane thermal cracking unit
[0034] 4. Stove
[0035] 5 Heat exchanger
[0036] 6 Cooling device
[0037] 100,200,300 Carbon dioxide fixation equipment DETAILED DESCRIPTION
[0038] The following describes the implementation of the present invention through specific embodiments, and those skilled in the art can understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified and changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.
[0039] First embodiment
[0040] First, please refer to Figure 1 , Figure 1 FIG. 1 is a schematic diagram of a carbon dioxide fixation device 100 according to a first embodiment of the present invention. Figure 1 As shown, the present invention provides a carbon dioxide fixation device 100, which includes: a methanation reaction device 1, a temperature control device 2, a methane thermal cracking device 3 and a furnace 4. In addition, in the carbon fixation device 100, the methanation reaction device 1, the temperature control device 2, the methane thermal cracking device 3 and the furnace 4 are connected to each other in this order, that is, one side of the methanation reaction device 1 is connected to one side of the temperature control device 2, the other side of the temperature control device 2 is connected to one side of the methane thermal cracking device 3, and the other side of the methane thermal cracking device 3 is connected to one side of the furnace 4. The following is a detailed description of each device.
[0041] Methanation reaction unit 1
[0042] The methanation reaction device 1 is used to react carbon dioxide with hydrogen and convert it into methane, that is, to perform a methanation reaction of carbon dioxide (CO2+4H2→CH4+2H2O). Generally speaking, the methanation reaction of carbon dioxide can be carried out at normal pressure and a reaction temperature of 200 to 500° C., and the volume ratio of carbon dioxide to hydrogen can be 1:2 to 1:5.
[0043] Furthermore, as a preferred embodiment, the weight hourly space velocity (WHSV) of the carbon dioxide feed can be set to 200-20000 mL / g / h, and the methanation reaction can be carried out in the above-mentioned methanation reaction device 1 under the above-mentioned reaction conditions.
[0044] Furthermore, as a preferred embodiment, the source of hydrogen in the methanation reaction device 1 is hydrogen produced by another water electrolysis device (not shown) or a methane thermal cracking device 3. In addition, the energy source required by the carbon fixation device of the present invention can be renewable energy (such as solar energy or wind energy), thereby providing the energy required by the methanation reaction device 1, the methane thermal cracking device 3 and the water electrolysis device, so as to achieve the effect of energy recycling and removal of carbon dioxide.
[0045] Temperature control device 2
[0046] As mentioned above, because there is a difference in reaction temperature between the methanation reaction of carbon dioxide and the thermal cracking reaction of methane, it is difficult to integrate the methanation reaction device 1 and the methane thermal cracking device 3, and if the heat of the methane thermal cracking device 3 and / or the furnace 4 is directly transferred to the methanation reaction device 1, the problem of catalyst deactivation in the methanation reaction device 1 may occur. Therefore, the temperature control device 2 is used to block the heat from the methane thermal cracking device 3 and the furnace 4, and by adjusting the flow rate of the cold fluid, the methanation reaction device 1 is controlled to a suitable reaction temperature range. In addition, the temperature control device 2 can also absorb the heat generated by the exothermic reaction of the methanation reaction device 1 through the cold fluid to avoid the catalyst deactivation caused by overheating of the methanation reaction device 1.
[0047] Next, please refer to Figure 4 , Figure 4 Schematic diagram of the temperature control device 2 of the present invention. Figure 4 As shown, the temperature control device 2 includes a tube layer 21 and a shell layer 22 surrounding the tube layer 21, wherein the tube layer 21 includes a tube layer inlet 211, and the shell layer 22 includes a shell layer inlet 221. In order to achieve the effect of blocking heat and / or absorbing heat, cold fluid is introduced into the tube layer 21 and the shell layer 22 through the tube layer inlet 211 and the shell layer inlet 221 respectively.
[0048] Furthermore, as for the cold fluid, as long as it can achieve the effect of blocking heat and / or absorbing heat, there is no particular limitation, but from the perspective of cost and safety, the cold fluid is preferably water. In addition, the methanogenic synthesis gas product (mainly comprising CO2, H2 and CH4) produced after the methanogenic reaction device 1 reacts can also be used as a low-temperature fluid to increase its temperature and facilitate the thermal cracking reaction of methane, thereby achieving the effect of saving energy. That is to say, in the embodiment, the methanogenic synthesis gas product and water that can be provided from the outside are used as low-temperature fluid and cold fluid respectively. In addition, in a preferred embodiment, water flows in the tube layer 21 and methanogenic synthesis gas flows in the shell layer 22. Among them, the flow rate of water can be 50 to 1500 ml / h. Within this flow range, the temperature of the methanogenic reaction device 1 can be controlled within the range of 150 to 450°C.
[0049] Then, please refer to Figure 5 , Figure 5 Schematic diagram of the tube layer 21 of the present invention. Figure 5 As shown, the pipe layer 21 of the temperature control device 2 is a multi-turn spiral pipe, that is, the pipe is designed to surround the barrel in a multi-turn spiral.
[0050] At Figure 5In the embodiment, the tube layer 21 can be divided into a spiral tube 21a near the inlet of the methanation reaction device and a spiral tube 21b near the outlet of the methanation reaction device, and the number of turns of the spiral tube 21a near the inlet of the methanation reaction device and the spiral tube 21b near the outlet of the methanation reaction device can be the same or different. However, considering that the methanation reaction of carbon dioxide is an exothermic reaction, heat is more likely to accumulate at the inlet of the methanation reaction device 1. Therefore, in order to improve the uniformity of the temperature distribution of the methanation reaction device 1, the number of turns of the spiral tube 21a near the inlet of the methanation reaction device (relative to the inlet position of the methanation reaction device) is preferably greater than the number of turns of the spiral tube 21b near the outlet of the methanation reaction device (relative to the outlet position of the methanation reaction device). In a preferred embodiment, the number of turns of the spiral tube 21a near the inlet of the methanation reaction device relative to the number of turns of the spiral tube 21b near the outlet of the methanation reaction device is 1.5:1 to 3:1, and preferably 2:1.
[0051] Methane thermal cracking unit 3
[0052] The methane thermal cracking device 3 is used to perform a thermal cracking reaction of methane (CH4→C+2H2) to thermally crack methane into solid carbon and hydrogen. Generally speaking, the thermal cracking reaction of methane can be carried out at normal pressure and a reaction temperature of 600-1100°C.
[0053] Furthermore, as a preferred embodiment, the weight hourly space velocity (WHSV) of the methane feed can be set to 100-2000 mL / g / h, and the methane thermal cracking reaction can be carried out in the above-mentioned methane thermal cracking unit 3 under the above-mentioned reaction conditions.
[0054] Furthermore, as a preferred embodiment, the pyrolysis gas containing hydrogen, unreacted methane, and pyrolysis byproduct CO etc. remaining after the reaction in the methane pyrolysis device 3 can be burned back to the furnace 4 to provide a heat source for the furnace 4, thereby reducing fuel loss. In addition, the hydrogen generated by the methane pyrolysis device 3 can also be used as a hydrogen source for the methanation reaction device 1.
[0055] Furthermore, the heat source of the methane thermal cracking device 3 can come from the combustion heat of the furnace 4 or the waste heat from the outside (such as the high-temperature exhaust gas of a cement plant).
[0056] Next, the methanation reaction device 1 and the methane thermal cracking device 3 can use a catalyst containing a metal component and a carrier. Here, the metal can be one or more of nickel, iron and cobalt, preferably nickel, and the metal content in the catalyst is 5 to 50 wt%. In addition, the carrier can use one or more of CeO2, La2O3, SiO2, Al2O3 and activated carbon, preferably Al2O3. The catalyst used in the methanation reaction device 1 and the methane thermal cracking device 3 is not particularly limited, as long as it can carry out the methanation reaction of carbon dioxide and the thermal cracking reaction of methane.
[0057] Stove 4
[0058] The furnace 4 is a device for providing heat, for example, heat can be provided to the methane thermal cracking device 3 by heat conduction. In addition, in the furnace 4, a combustion reaction can be performed to provide heat, for example, a fuel (such as hydrogen) mixed with air in a specific ratio is used to burn and heat up to control the temperature of the furnace.
[0059] Second embodiment
[0060] Next, please refer to Figure 2 , Figure 2 FIG. 2 is a schematic diagram of a carbon dioxide fixation device 200 according to a second embodiment of the present invention. Figure 2 As shown, the present invention provides a carbon dioxide fixation device 200, which includes: a methanation reaction device 1, a temperature control device 2, a methane thermal cracking device 3, a furnace 4, a heat exchanger 5 and a water cooling device 6. Here, the heat exchanger 5 is connected to the methanation reaction device 1, and cools down the methanation synthesis gas product from the methanation reaction device 1. The water cooling device 6 is connected to the heat exchanger 5, and removes water from the cooled product.
[0061] By removing water from the product (methanation synthesis gas) of the methanation reaction device 1 through the heat exchanger 5 and the water-removing device 6, it is possible to prevent water from reacting in the subsequent methane thermal cracking device 3 and affecting the thermal cracking reaction efficiency of methane. Here, because the heat exchanger 5 and the water-removing device 6 will cool the methanation synthesis gas, in the second embodiment, it is preferred that the methanation synthesis gas is used as a low-temperature fluid and input into the shell 22 of the temperature control device 2 to increase its temperature, so as to facilitate the subsequent thermal cracking reaction of methane.
[0062] In addition, regarding the methanation reaction device 1, the temperature control device 2, the methane thermal cracking device 3 and the furnace 4, since they are the same as the methanation reaction device 1, the temperature control device 2, the methane thermal cracking device 3 and the furnace 4 of the first embodiment, they are given the same symbols and their description is omitted.
[0063] Third embodiment
[0064] Then, please refer to Figure 3 , Figure 3 FIG. 3 is a schematic diagram of a carbon dioxide fixation device 300 according to a third embodiment of the present invention. Figure 3 As shown, the present invention provides a carbon dioxide fixation device 300, which includes: a methanation reaction device 1, a temperature control device 2, a methane thermal cracking device 3 and a furnace 4. Here, the carbon fixation device 300 is a concentric circle structure, the innermost circle is the furnace 4, and from the inside to the outside are the methane thermal cracking device 3, the temperature control device 2 and the methanation reaction device 1.
[0065] By using the concentric structure of the carbon fixation equipment 300, the heat conduction can be uniformed, and each reaction can be carried out efficiently to save energy. In addition, the methanation reaction device 1, the temperature control device 2, the methane thermal cracking device 3 and the furnace 4 are the same as those of the methanation reaction device 1, the temperature control device 2, the methane thermal cracking device 3 and the furnace 4 of the first embodiment, so the same symbols are given and their descriptions are omitted.
[0066] Example
[0067] The carbon fixation equipment of the second embodiment is designed as a concentric circle structure, and a reaction is carried out; wherein, the number of turns of the spiral pipe near the inlet of the methanation reaction device in the pipe layer in the temperature control device is 8 turns, and the number of turns of the spiral pipe near the outlet of the methanation reaction device is 4 turns.
[0068] First, in the furnace, hydrogen is mixed with air to burn and heat up, and the volume ratio of air to hydrogen (air-fuel ratio) is 12:1 to 14:1. As a result, the temperature of the furnace is controlled at 770-828°C, and the catalyst bed of the methanation reaction device (also referred to as the methanation catalyst bed) is gradually heated up by heat conduction through the furnace. When the temperature of the methanation catalyst bed reaches 187°C, the volume concentration ratio of hydrogen and carbon dioxide is controlled by a mass flow controller (MFC) to be about 4:1, and the concentration of H2 is confirmed to be 79% and the concentration of CO2 is 19% by a non-dispersive infrared gas sensor (NDIR). The feed rate is set to 8918ml / min and the weight hourly space velocity (WHSV) is set to 399ml / h / g to transport hydrogen and carbon dioxide to the methanation reaction device for reaction.
[0069] The catalyst filled in the methanation catalyst bed is 1.34 kg of a supported nickel-based catalyst (Ni content>45%), and the carrier is alumina. After hydrogen and carbon dioxide are introduced, the methanation catalyst bed begins to heat up due to the exothermic reaction. At this time, water at room temperature is introduced into the temperature control device as a cold fluid for cooling, and the water volume is 343 ml / h. Finally, the temperature for the methanation reaction is 333 to 363 degrees, the gauge pressure is 0.15 to 0.2 bar, the outlet synthesis gas flow rate is 3420 ml / min, and the CO2 conversion rate is 93%. It can be seen that by using the carbon fixation equipment of the present invention, a result of a carbon dioxide conversion rate of 70% to 95% can be obtained. Then, the methanation synthesis gas is cooled to room temperature by a heat exchanger and a water cooling device, and the amount of condensed water removed in the water cooling device is 2.1 g / min. In addition, the concentration of the main components of the methanation synthesis gas is as shown in Table 1 below.
[0070] Table 1
[0071] Analytical Instruments <![CDATA[CO2]]> <![CDATA[H2]]> <![CDATA[CH4]]> NDIR 4％ 48％ 45％
[0072] Next, the methanogenic synthesis gas from the methanogenic reaction unit is preheated to 358°C through the shell of the temperature control device and then enters the methane thermal cracking unit. The weight hourly space velocity (WHSV) of the feed is 127 ml / h / g, the reaction temperature of the thermal cracking catalyst bed is 665°C, and the outlet cracking gas flow rate is 4500 ml / min. The main component concentrations of the cracking gas as the outlet product are shown in Table 2 below. After measurement and calculation, the carbon fixation amount is 20.4 g / h, and the carbon fixation rate is about 38.3%. In addition, the carbon fixation rate is calculated as: 1-(the number of moles of unconverted carbon / the number of moles of introduced carbon). In this embodiment, the carbon fixation rate is 1-[(4500x(0.48%+12.28%+10.46%)) / (8918x19%)]=about 38.3%.
[0073] Table 2
[0074] Analytical Instruments <![CDATA[CO2]]> CO <![CDATA[H2]]> <![CDATA[CH4]]> NDIR 0.48％ 12.28％ 76％ 10.46％
[0075] In addition, the calorific value of the above cracking gas is 43.5MJ / kg after NDIR analysis, so it can be burned back to provide furnace heat. In addition, after SEM analysis, the solid carbon product obtained in this embodiment is mostly high value-added carbon nanotubes, and a small amount is granular carbon-containing substances. The diameter of the carbon nanotubes is about 50-150nm.
[0076] It can be seen that the carbon fixation device of the present invention can save the space required for placing the reaction device and can easily perform carbon fixation of the gas containing carbon dioxide. Furthermore, the problem of catalyst deactivation in the methanation reaction device can also be avoided.
[0077] The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.
Claims
1. A carbon dioxide fixation device, characterized in that: Include: A methanation reaction device that reacts carbon dioxide with hydrogen and converts it into methane; A temperature control device comprising a tube layer and a shell layer surrounding the tube layer; a methane thermal cracker that thermally cracks methane into solid carbon and hydrogen; and stove; Wherein, in the carbon fixation equipment, the methanation reaction device, the temperature control device, the methane thermal cracking device and the furnace are connected to each other in this order.
2. The carbon dioxide fixation equipment according to claim 1, characterized in that: The carbon fixation equipment is a concentric circle structure.
3. The carbon dioxide fixation equipment according to claim 1, characterized in that: The tube layer is a spiral tube wound in multiple turns.
4. The carbon dioxide fixation equipment according to claim 3, characterized in that: The tube layer includes a spiral tube near the inlet of the methanation reaction device and a spiral tube near the outlet of the methanation reaction device, and the ratio of the number of turns of the spiral tube near the inlet of the methanation reaction device to the number of turns of the spiral tube near the outlet of the methanation reaction device is 1.5:1 to 3:
1.
5. The carbon dioxide fixation equipment according to claim 1, characterized in that: Also includes: a heat exchanger connected to the methanation reaction device and cooling the product from the methanation reaction device; The water-removing device is connected to the heat exchanger and removes water from the cooled product.
6. The carbon dioxide fixation equipment according to claim 1, characterized in that: The source of hydrogen in the methanation reaction device is hydrogen produced by a water electrolysis device or the methane thermal cracking device.
7. The carbon dioxide fixation equipment according to claim 1, characterized in that: The heat source in the methane thermal cracking device is the combustion heat from the furnace or external waste heat.
8. The carbon dioxide fixation equipment according to claim 1, characterized in that: The cracked gas produced by the methane thermal cracking device is burned back to provide heat to the furnace.
9. The carbon dioxide fixation equipment according to any one of claims 1 to 8, characterized in that: The tube layer has water flowing therein and the shell layer has methanogenic synthesis gas flowing therein.
10. The carbon dioxide fixation equipment according to claim 9, characterized in that: The flow rate of the water is 50 to 1500 ml / h.