Device and method for forming carbon dioxide hydrate by rolling gravel with liquid water film

Abstract

The present application relates to a device and method for forming carbon dioxide hydrate by rolling gravel with liquid water film, and relates to the field of carbon capture technology. The device includes a frame and a motor, a linkage shaft and a reaction cylinder installed on the frame. The motor is used to drive the linkage shaft to rotate. The reaction cylinder is rotatably arranged on the linkage shaft, and the reaction cylinder is driven to rotate by the linkage shaft; the reaction cylinder includes a cylinder body and a paddle plate arranged inside the cylinder body. The cylinder body is provided with a rotating interface, and the rotating interface is used to pass flue exhaust gas. The cylinder body is used to load a mixture of gravel and water. The reaction cylinder is used to rotate under a preset low temperature environment, and uses flue exhaust gas, gravel and water to generate solid hydrate. The device and method can efficiently capture and separate carbon dioxide from flue exhaust gas.

Description

Technical Field

[0001] The present application relates to the field of carbon capture technology, and in particular to a device and method for forming carbon dioxide hydrate by rolling gravel with a liquid water film. Background Art

[0002] Carbon dioxide is an important substance that causes the greenhouse effect. In the next few decades, fossil fuels will still dominate the world's energy supply, and carbon emission reduction still faces huge challenges. At present, the international community, based on relevant requirements in the field of environment, widely believes that the in-depth development of carbon dioxide capture and storage (CCS) technology is of great significance to alleviating global warming. How to capture and separate carbon dioxide from mixed gases is the premise and basis for reducing carbon dioxide emissions.

[0003] Traditional carbon capture methods include absorption, adsorption, low-temperature separation, metal oxide, membrane separation, etc. Among them, chemical absorption is relatively mature and is suitable for conditions where the carbon dioxide concentration is not high and the pressure is normal. However, the amount of absorbent used is large, and it needs to be replenished during the cycle. The reagent requirements are high, and the regeneration process has high energy consumption. Although the membrane separation method has a simple process and is easy to operate, it has high requirements for the raw gas, and pre-treatment, dehydration and filtration are required, and the purity of the obtained product is not high. Therefore, methods and equipment with high capture efficiency and low capture cost are urgently needed.

[0004] Due to the physical and chemical properties of hydrate structure and gas storage characteristics, the technology of recovering and storing carbon dioxide using gas hydrate method has become an emerging research hotspot in recent years. Compared with traditional separation methods, the separation of carbon dioxide gas in flue gas using hydrate method can greatly reduce the separation cost while effectively improving the separation efficiency. Gas hydrate is a compound composed of water molecules and gas molecules under high pressure and low temperature conditions. Under appropriate low temperature and high pressure conditions, water molecules form cage structures with different shapes and sizes through hydrogen bonding, and different types of gas molecules are enclosed in this structure to form gas hydrates. The principle of using hydrate method to separate mixed gases is that the phase equilibrium difference between binary and multi-component gases when forming hydrates is large, so the gas that is easier to form gas hydrates enters the hydrate phase, and the gas that is difficult to form gas hydrates is retained in the gas phase, thereby achieving the separation of mixed gases.

[0005] In the hydrate carbon capture technology, the conditions required for the formation of carbon dioxide hydrates are milder than those for nitrogen hydrates. For example, at 273.15K, the pressure required for the formation of carbon dioxide hydrates is 1.24MPa, while the pressure required for the formation of nitrogen hydrates is 16.3MPa. Therefore, the hydrate method can be applied to the capture of greenhouse gases such as carbon dioxide. In addition, the energy density of gas hydrates is very high. One volume of hydrate can release about 170 volumes of gas under standard conditions. However, the hydrate nucleation process has a random characteristic, and there is a long induction period before nucleation. In addition, the formation of hydrates releases heat. If the generated heat cannot be removed in time, it will inhibit the further formation of hydrates. This means that, in general, the formation efficiency of hydrates is low. When hydrates are formed, the hydrate layer formed at the water-gas interface will significantly reduce the permeability of the gas. Therefore, in the growth stage after the hydrate nucleation, the material transmission capacity of the gas will gradually decrease significantly. This means that, in general, the final energy storage capacity of hydrates is low. Moreover, the hydrates generated under the existing technology are mostly loose snowflakes or hydrate slurries, which occupy most of the growth space and are not conducive to efficient and continuous reaction. Therefore, although gas hydrates have great potential in the capture and storage of carbon dioxide, the relatively low capture rate and low gas capture capacity in the general hydrate carbon capture process limit the commercial application scale of hydrate carbon capture technology. Summary of the invention

[0006] The purpose of the present application is to provide a device and method for forming carbon dioxide hydrate by rolling gravel with liquid water film, and the device and method can efficiently capture and separate carbon dioxide from flue exhaust gas.

[0007] In order to achieve the above-mentioned purpose, in a first aspect, the present invention provides a device for forming carbon dioxide hydrate by rolling gravel with a liquid water film, the device comprising a frame and a motor, a linkage shaft and a reaction cylinder mounted on the frame, the motor is used to drive the linkage shaft to rotate, the reaction cylinder is rotatably arranged on the linkage shaft, and the reaction cylinder is driven to rotate by the linkage shaft;

[0008] The reaction cylinder includes a cylinder body and a paddle plate arranged inside the cylinder body. A rotating interface is arranged on the cylinder body, and the rotating interface is used to introduce flue exhaust gas. The cylinder body is used to load a mixture of gravel and water. The reaction cylinder is used to rotate under a preset low temperature environment and utilize the flue exhaust gas, gravel and water to generate solid hydrates.

[0009] In an optional embodiment, there are two linkage shafts, which are arranged in parallel and rotate in the same direction at the same speed, and the reaction cylinder is supported in the middle of the two linkage shafts.

[0010] In an optional embodiment, the linkage shaft includes a shaft body and a plurality of friction wheels installed on the shaft body at intervals, and the body of the reaction cylinder is supported on the friction wheels of the two linkage shafts.

[0011] In an optional embodiment, the reaction cylinder further comprises two limiting rings sleeved on the cylinder body, and the two limiting rings are respectively arranged on both sides of all the friction wheels to prevent the reaction cylinder from moving on the linkage shaft.

[0012] In an optional embodiment, the reaction cylinder includes two paddles, both of which extend along the axial direction of the cylinder body, and the two paddles are located at two ends of the circumference of the cylinder body.

[0013] In a second aspect, the present invention provides a method for forming carbon dioxide hydrate by rolling gravel onto a liquid water film, the method using the device of the aforementioned embodiment, the method comprising:

[0014] S1: mixing gravel and water to form a mixture, wherein the average particle size of the gravel is not less than 2 mm;

[0015] S2: Load the mixture of gravel and water into the reaction cylinder in the cold storage;

[0016] S3: introducing flue gas into the reaction tube until the pressure in the reaction tube reaches a preset value;

[0017] S4: Start the motor to rotate the reaction tube and generate solid hydrate using flue gas, sand and water.

[0018] In an optional embodiment, S4 includes:

[0019] During the process of generating solid hydrate, flue gas is continuously introduced into the reaction tube to maintain the pressure in the reaction tube at a preset value.

[0020] In an optional embodiment, S4 includes:

[0021] After the solid hydrate is generated, the temperature of the cold storage is controlled below -5°C to fully freeze the generated solid hydrate.

[0022] In an optional embodiment, the average particle size of the gravel ranges from 2 mm to 4 mm.

[0023] In an optional implementation, the preset pressure value is 8.5 MPa.

[0024] Through the above technical scheme, the angular structure of the gravel surface can be used to induce the hydrate formation reaction, thereby avoiding the use of promoters, reducing economic costs and environmental pollution risks; the gravel can be repeatedly immersed in and out of the water at the bottom of the reaction tube, so that the water is continuously coated on the surface of the gravel layer by layer, and under a preset pressure value and a preset low temperature environment, accompanied by the rapid generation of solid hydrates, the carbon dioxide in the flue gas will be efficiently captured and separated; the amount of water used in the reaction process no longer depends on the effective pore volume in the gravel, and can be mixed with the gravel in any proportion, thereby greatly improving the efficiency of the induced hydrate nucleation reaction of the angular structure on the surface of the gravel.

[0025] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic structural diagram of a first perspective of an apparatus for forming carbon dioxide hydrate by rolling gravel onto a liquid water film provided in an embodiment of the present application;

[0028] Figure 2 A schematic structural diagram of a device for forming carbon dioxide hydrate by rolling gravel onto a liquid water film provided in an embodiment of the present application from a second perspective;

[0029] Figure 3 Schematic diagram of loading the reaction cylinder with a mixture of gravel and water;

[0030] Figure 4 It is a schematic diagram of the reaction cylinder rotating and generating solid hydrate;

[0031] Figure 5 Schematic diagram of the generation of bubbles due to local decomposition of solid hydrate.

[0032] Icons: 1-frame; 2-motor; 3-linkage shaft; 31-shaft body; 32-friction wheel; 4-reaction cylinder; 5-cylinder body; 6-limiting ring; 7-sliding piece; 8-gravel; 9-water; 10-solid hydrate; 11-bubble. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0034] In the description of this application, it should be noted that the terms "inside", "outside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0035] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0036] Please refer to Figure 1 and Figure 2 The present embodiment provides a device for forming carbon dioxide hydrate by rolling gravel with a liquid water film (hereinafter referred to as: device), the device includes a frame 1 and a motor 2, a linkage shaft 3 and a reaction tube 4 installed on the frame 1, the motor 2 is used to drive the linkage shaft 3 to rotate, the motor 2 can drive the linkage shaft 3 to rotate through a belt connection, the reaction tube 4 is rotatably arranged on the linkage shaft 3, and the reaction tube 4 is driven to rotate by the linkage shaft 3.

[0037] Specifically, there are two linkage shafts 3, which are arranged in parallel and rotate in the same direction at the same speed, and the reaction cylinder 4 is supported between the two linkage shafts 3. The linkage shaft 3 includes a shaft body 31 and a plurality of friction wheels 32 installed on the shaft body 31 at intervals, and the cylinder body 5 of the reaction cylinder 4 is supported on the friction wheels 32 of the two linkage shafts 3.

[0038] The reaction cylinder 4 further includes two limiting rings 6 sleeved on the cylinder body 5 . The two limiting rings 6 are respectively arranged on both sides of all the friction wheels 32 to prevent the reaction cylinder 4 from moving on the linkage shaft 3 .

[0039] Please refer to Figures 3 to 5The reaction cylinder 4 includes a cylinder body 5 and a paddle plate 7 disposed inside the cylinder body 5. The reaction cylinder 4 includes two paddle plates 7, both of which extend along the axial direction of the cylinder body 5, and the two paddle plates 7 are located at both ends of the circumference of the cylinder body 5. A rotating interface is provided on the cylinder body 5, and the rotating interface is used to pass flue gas. The cylinder body 5 is used to load a mixture of gravel 8 and water 9. The reaction cylinder 4 is used to rotate under a preset low temperature environment, and the flue gas, gravel 8 and water 9 are used to generate solid hydrate 10.

[0040] This embodiment also provides a method for forming carbon dioxide hydrate by rolling gravel onto a liquid water film (hereinafter referred to as the method), the method adopts the above-mentioned device, and the method comprises the following steps:

[0041] S1: Mix gravel 8 and water 9 to form a mixture.

[0042] The average particle size of the gravel 8 is not less than 2 mm. Preferably, the average particle size of the gravel 8 is in the range of 2 mm to 4 mm.

[0043] S2: A mixture of gravel 8 and water 9 is placed into the reaction cylinder 4 in the cold storage.

[0044] The reaction tube 4 can withstand a gas pressure of 15 MPa. At this time, the mixture of water 9 and gravel 8 will be located at the bottom of the reaction tube 4 under the action of gravity. Figure 3 As shown, the gravel 8 is completely submerged in the water 9 and is fully soaked.

[0045] S3: introducing flue gas into the reaction tube 4 until the pressure in the reaction tube 4 reaches a preset pressure value.

[0046] Specifically, the reaction cylinder 4 is connected to an external high-pressure gas source via a rotating interface, and during the rotation of the reaction cylinder 4, the internal pressure thereof is stably maintained at a preset pressure value, wherein the preset pressure value is 8.5 Mpa.

[0047] S4: Start the motor 2 to rotate the reaction tube 4, and use the flue gas, gravel 8 and water 9 to generate solid hydrate 10.

[0048] Specifically, a paddle plate 7 is installed inside the reaction tube 4, and the paddle plate 7 rotates synchronously with the reaction tube 4, so that the gravel 8 at the bottom of the reaction tube 4 can be continuously scooped out from the water 9 to a higher position, such as Figure 4 shown.

[0049] Since the particle size of the gravel 8 in the reaction tube 4 is relatively large, with an average particle size of 2 mm to 4 mm, its ability to absorb water 9 is relatively weak. When the gravel 8 is scooped to a higher position by the prying piece 7, as shown in FIG. Figure 4As shown, water 9 can flow downward in the gravel 8. At this time, the surface of the gravel 8 exposed from the water 9 is covered with a thin layer of water film, and the carbon dioxide can be fully dissolved in this water film and converted into solid hydrate 10.

[0050] The reaction tube 4 is driven by the motor 2 to continuously rotate, and the gravel 8 inside the reaction tube 4 is repeatedly scooped out of the water 9 by the paddle 7 and poured back into the water 9. This cycle occurs under a preset pressure value and a preset low temperature environment. Therefore, the carbon dioxide in the flue gas will be converted into solid hydrate 10 on the surface of the gravel 8 together with the water 9, and will be coated on the surface of the gravel 8 layer by layer. The newly generated solid hydrate 10 can play a similar role to the gravel 8, and the solid hydrate 10 can coat a new base medium, further promoting the continuous formation reaction of the solid hydrate 10.

[0051] After the solid hydrate 10 is rapidly generated on the surface of the gravel 8, the gravel 8 and the solid hydrate 10 are poured into the water 9 again as the reaction tube 4 continues to rotate, and a local decomposition reaction occurs under the action of the water 9, releasing bubbles 11 of carbon dioxide. Please refer to Figure 5 The released bubbles 11 disturb the water 9, further increasing the solubility of the gas in the water 9, thereby accelerating the hydrate formation reaction rate in the entire reaction process.

[0052] During the process of generating the solid hydrate 10 , flue gas is continuously introduced into the reaction tube 4 so that the pressure inside the reaction tube 4 is maintained at a preset pressure value.

[0053] After the solid hydrate 10 is generated, the temperature of the cold storage is controlled to be below -5°C to fully freeze the generated solid hydrate 10 so that it can maintain a stable state for a long time under normal pressure. After being frozen, the solid hydrate 10 will quickly enter a "self-protection" state, and then it can maintain stability without decomposition under normal pressure. At this time, the kettle covers at both ends of the reaction cylinder 4 can be opened and the solid hydrate 10 can be taken out for the next step of collection, storage, transportation and other subsequent processing operations.

[0054] The technical concept of the device and method for forming carbon dioxide hydrate by rolling gravel with liquid water film provided in this embodiment is summarized as follows:

[0055] With the help of the gravel 8 continuously rolling in the cylindrical reaction tube 4, a water film is coated on the surface of the gravel 8, and solid hydrates 10 are quickly formed between the gravel 8, and finally the purpose of efficiently capturing and separating carbon dioxide in flue gas by the hydrate method is achieved. Gravel 8 is widely distributed in nature, the raw materials are easily available and economical. In addition, the appearance of gravel 8 is irregular, and the particles themselves have many angular structures, which are conducive to rapid nucleation in the hydrate formation reaction and induce rapid nucleation of hydrates. The gravel 8 is placed in the reaction tube 4, and with the help of the continuous rolling of the reaction tube 4, the gravel 8 is repeatedly immersed in and leached out of the water 9 at the bottom of the reaction tube 4. When the gravel 8 is soaked in the water 9 and fished out, a thin water film is coated on the surface of the gravel 8. At this time, the contact area between the gas / liquid phase of carbon dioxide is greatly increased, and the hydrate formation reaction proceeds rapidly on this water film. Afterwards, driven by the rotation of the reaction tube 4, the gravel 8 is immersed in the water 9 at the bottom of the reaction tube 4 again. With the rolling of the reaction tube 4, the gravel 8 will be fished out from the bottom water 9 again. The hydrates previously generated on the surface of the gravel 8 can serve as an inducing structure for the subsequent water film layer to be converted into hydrates, promoting the water film on the surface of the gravel 8 to be quickly converted into hydrates and wrapped on the surface of the gravel 8. With the continuous rolling of the reaction tube 4, the solid hydrates 10 will be continuously wrapped on the surface of the gravel 8 layer by layer. Under the preset pressure value and the preset low temperature environment, with the rapid generation of solid hydrates 10, the carbon dioxide component in the flue gas will be efficiently captured and separated.

[0056] The working process of the device for forming carbon dioxide hydrate by rolling gravel with liquid water film provided in this embodiment is summarized as follows:

[0057] First, gravel 8 and water 9 are mixed to form a mixture, and loaded into the reaction tube 4 in the cold storage, wherein the mixture of gravel 8 and water 9 will be located at the bottom of the reaction tube 4; then, flue gas is filled into the reaction tube 4 until a preset pressure value is reached in the reaction tube 4; then, the motor 2 is started to drive the reaction tube 4 to rotate, at this time, the gravel 8 in the reaction tube 4 will repeatedly immerse in and out of the water 9 at the bottom of the reaction tube 4, and under the preset pressure value and preset low temperature environment, the solid hydrate 10 will be coated on the surface of the gravel 8 layer by layer, and with the continuous generation of the solid hydrate 10, the carbon dioxide in the flue gas is captured and separated. Finally, after the capture and separation process of the carbon dioxide in the entire flue exhaust gas is completed, the solid hydrate 10 finally obtained will be frozen at negative temperature (-5°C and below), and the solid hydrate 10 will enter a "self-protection" state, that is, it will remain stable for a long time without decomposing under normal pressure conditions. At this time, the frozen solid hydrate 10 will be taken out of the reaction cylinder 4, and the next subsequent treatment such as collection, storage, and transportation can be carried out, and the treated exhaust gas that meets the standards can be discharged into the atmosphere.

[0058] The device and method for forming carbon dioxide hydrate by rolling gravel with liquid water film provided in this embodiment have the following beneficial effects:

[0059] Gravel 8 is used as a promoting medium for the hydrate formation reaction. Gravel 8 is widely distributed in nature and the raw materials are easily available, which has good economic efficiency. Taking advantage of the fact that gravel 8 contains rich angular structures, these angular structures are used as nucleation advantages for the hydrate formation reaction. Under low temperature and high pressure environmental conditions, these angular structures can induce rapid nucleation of hydrates. In addition, this method also utilizes the fact that gravel 8 with larger particle size has a weaker ability to absorb water 9, and water 9 will quickly seep downward under the action of gravity. With the help of continuous rolling operation in the reaction tube 4, the surface of gravel 8 will be continuously coated with water film layer by layer. This method can achieve a similar effect as a surfactant, effectively increase the gas / liquid phase contact area, and improve the efficiency of the hydrate formation reaction. Therefore, this method achieves a function similar to that of a chemical surfactant by physical means, avoids the use of chemical promoters in the hydrate formation reaction, and further reduces the economic cost and the possibility of environmental pollution.

[0060] It should be noted that, in the absence of conflict, the features in the embodiments of this application may be combined with each other.

[0061] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for forming carbon dioxide hydrate by rolling gravel with liquid water film, characterized in that: The method adopts a device for forming carbon dioxide hydrate by rolling a liquid water film with gravel, the device comprising a frame (1) and a motor (2) mounted on the frame (1), a linkage shaft (3) and a reaction tube (4), the motor (2) being used to drive the linkage shaft (3) to rotate, the reaction tube (4) being rotatably arranged on the linkage shaft (3), the reaction tube (4) being driven to rotate by the linkage shaft (3), the number of the linkage shafts (3) being two, the two linkage shafts (3) being arranged in parallel and rotating in the same direction at the same speed, and the reaction tube (4) being supported between the two linkage shafts (3). The linkage shaft (3) comprises a shaft body (31) and a plurality of friction wheels (32) installed at intervals on the shaft body (31); the reaction cylinder (4) comprises a cylinder body (5) and a paddle (7) arranged inside the cylinder body (5); the cylinder body (5) of the reaction cylinder (4) is supported on the friction wheels (32) of the two linkage shafts (3); the reaction cylinder (4) further comprises two limiting rings (6) sleeved on the cylinder body (5); the two limiting rings (6) are respectively arranged on both sides of all the friction wheels (32) to prevent the reaction cylinder (4) from moving on the linkage shaft (3); The cylinder (5) is provided with a rotation interface, the rotation interface is used to introduce flue gas, the cylinder (5) is used to load a mixture of gravel (8) and water (9), the reaction cylinder (4) is used to rotate under a preset low temperature environment, and generate solid hydrate (10) by using the flue gas, gravel (8) and water (9), the reaction cylinder (4) comprises two paddle plates (7), the two paddle plates (7) both extend along the axial direction of the cylinder (5), and the two paddle plates (7) are located at two ends of the circumference of the cylinder (5); The method comprises: S1: mixing gravel (8) and water (9) to form a mixture, wherein the average particle size of the gravel (8) is not less than 2 mm; S2: Loading a mixture of gravel (8) and water (9) into a reaction cylinder (4) in a cold storage; S3: introducing flue gas into the reaction tube (4) until a preset pressure value is reached in the reaction tube (4); S4: starting the motor (2) to rotate the reaction tube (4) and generating solid hydrate (10) by using flue gas, gravel (8) and water (9).

2. The method for forming carbon dioxide hydrate by rolling gravel with liquid water film according to claim 1, characterized in that S4 include: During the process of generating the solid hydrate (10), flue gas is continuously introduced into the reaction tube (4) so ​​that the pressure inside the reaction tube (4) is maintained at a preset pressure value.

3. The method for forming carbon dioxide hydrate by rolling gravel with liquid water film according to claim 1, characterized in that S4 include: After the solid hydrate (10) is generated, the temperature of the cold storage is controlled to be below -5°C to fully freeze the generated solid hydrate (10).

4. The method for forming carbon dioxide hydrate by rolling gravel with liquid water film according to claim 1, characterized in that: The average particle size of the gravel (8) is in the range of 2 mm to 4 mm.

5. The method for forming carbon dioxide hydrate by rolling gravel with liquid water film according to claim 1, characterized in that: The preset pressure value is 8.5 MPa.

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