System and method for separating carbon dioxide gas by hydrate formation

Abstract

This invention discloses a system and method for separating carbon dioxide gas using a hydrate method. The system includes: a reaction vessel with an inner and outer cavity structure, the outer surface of which is equipped with a constant temperature layer; an external circulation unit that injects a high-concentration TBAB solution into the inner cavity and forms type A TBAB hydrate crystals therein, while the hydrate slurry flows from the inner cavity into the outer cavity and is discharged from the outer cavity for reuse; an inlet unit that injects a low-temperature, high-pressure mixed gas containing CO2 into the inner cavity; and an internal circulation unit that injects a low-concentration TBAB solution into the inner cavity, converting type A TBAB hydrate into type B TBAB hydrate while simultaneously using type A TBAB hydrate crystals as inducing particles to undergo a hydration reaction with the mixed gas in the inner cavity; after the reaction, the hydrate slurry dissolves and captures CO2 while the remaining liquid phase is discharged for reuse. This invention reduces energy consumption and, by adding inducing crystal nuclei, effectively shortens the induction time, achieving a continuous process of introducing inducing crystal nuclei and generating hydrates in a closed system, effectively improving separation efficiency.

Description

Technical Field

[0001] This invention relates to the field of gas separation technology using hydrates, and particularly to a system and method for separating carbon dioxide gas using a crystal nucleus-induced hydrate method. Background Technology

[0002] Against the backdrop of "carbon neutrality" and "carbon peaking," carbon dioxide capture and storage is an important part of reducing carbon emissions both domestically and internationally. Since carbon dioxide and water can form ice-like crystalline compounds, namely hydrates, under high pressure and low temperature, and different gas molecules require different pressure and temperature conditions to form hydrates, the hydrate method can be used for gas separation.

[0003] Gas separation processes based on hydrates have been extensively studied. However, hydrate-based gas separation methods also have their own problems. First, most current research is based on small-scale laboratory equipment, and most of these studies employ multi-stage separation methods, which increase energy consumption. Therefore, promoting gas hydrate formation has become a key focus in the industry to improve gas separation efficiency. In most ordinary tubular reactors, the fluid is in a laminar flow state within the pipe, resulting in weak gas-liquid mass transfer, slow and insufficient hydrate formation, and inadequate gas separation. Current separation devices mostly improve gas-liquid mass transfer by increasing the gas-liquid contact area and agitation to increase the hydrate formation rate. However, these methods require a certain induction time and relatively low temperature. Therefore, it is necessary to shorten the induction time and develop new hydrate-based separation processes based on other influencing factors of hydrates.

[0004] Chinese patent application CN104403711A discloses a method and apparatus for separating CO2 from biogas based on the hydrate method. The apparatus features a titanium-plated inner layer on the hydrate reaction vessel, solving the problem of hydrate slurry accumulation and poor circulation in the separated gas. It employs a dual cooling method: jacketed refrigeration and internal coil refrigeration, while also being covered with an insulation layer. This ensures a large cooling environment during the hydrate reaction, reducing heat loss, and maintaining a uniform temperature within the hydrate reaction vessel. While the patent has a simple structure, it yields homogeneous nucleated hydrates, although the reaction time is relatively long.

[0005] Therefore, there is an urgent need for a system and method for separating carbon dioxide gas using a hydrate method induced by crystal nuclei. This method would reduce energy consumption and, by adding induced crystal nuclei, effectively shorten the induction time, enabling a continuous process of introducing induced crystal nuclei and generating hydrates in a closed system, thereby effectively improving separation efficiency.

[0006] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a system and method for separating carbon dioxide gas using a nucleus-induced hydrate method. This method reduces energy consumption and effectively shortens the induction time by adding induced nuclei, enabling a continuous process of introducing induced nuclei and generating hydrates in a closed system, thereby effectively improving separation efficiency.

[0008] To achieve the above objectives, according to a first aspect of the present invention, a system for separating carbon dioxide gas by hydrate method is provided, comprising: a reaction vessel having an inner and outer cavity structure, wherein a constant temperature layer is provided on the outer surface of the inner cavity; an external circulation unit that injects a high-concentration TBAB solution into the inner cavity and forms type A TBAB hydrate crystals in the inner cavity, wherein the hydrate slurry flows from the inner cavity into the outer cavity and is discharged from the outer cavity for reuse; an inlet unit that injects a low-temperature, high-pressure mixed gas containing CO2 into the inner cavity; and an internal circulation unit that injects a low-concentration TBAB solution into the inner cavity, converting type A TBAB hydrate into type B TBAB hydrate while using type A TBAB hydrate crystals as inducing particles to undergo a hydration reaction with the mixed gas in the inner cavity; wherein the hydrate slurry after reaction is dissolved to capture CO2 while the remaining liquid phase is discharged for reuse.

[0009] Furthermore, in the above technical solution, the constant temperature layer is rotatable; when the constant temperature layer is rotated to the first position, the bottom filter hole of the constant temperature layer is aligned with the bottom filter hole of the inner cavity, which is used to discharge the hydrate slurry formed by the external circulation unit to the outer cavity; when the constant temperature layer is rotated to the second position, the bottom filter hole of the constant temperature layer is staggered with the bottom filter hole of the inner cavity, so that the inner and outer cavities are relatively closed.

[0010] Furthermore, in the above technical solution, the inner cavity of the reactor may be provided with: a first liquid inlet for receiving a high-concentration TBAB solution; a second liquid inlet for receiving a low-concentration TBAB solution; a gas inlet for receiving a low-temperature, high-pressure mixed gas containing CO2; and an exhaust port for discharging the gas remaining after the hydration reaction.

[0011] Furthermore, in the above technical solution, a stirring paddle is provided at the bottom of the inner cavity of the reactor. The stirring paddle is connected by a stirring shaft that passes through the inner cavity and the insulation layer, and is used to stir the TBAB solution in the inner cavity during the hydration reaction.

[0012] Furthermore, in the above technical solution, an outer cavity outlet may be provided at the bottom of the outer cavity; and an inner cavity outlet may be provided on the lower side wall of the inner cavity.

[0013] Furthermore, in the above technical solution, the filter holes at the bottom of the constant temperature layer and the filter holes at the bottom of the inner cavity can be arranged in layers at uniform intervals around the circumference.

[0014] Furthermore, in the above technical solution, the external circulation unit may include a high-concentration storage tank and a first circulation pump.

[0015] Furthermore, in the above technical solution, the air intake unit can be supplied with air through a high-pressure gas cylinder, and the cooled mixed gas enters the buffer gas cylinder through parallel air intake pipelines. After obtaining the mixed gas at a preset pressure in the buffer gas cylinder, it is injected into the inner cavity of the reactor.

[0016] Furthermore, in the above technical solution, the intake unit may further include: a booster subunit, which is connected in parallel in the intake pipeline and adjusts the pressure of the mixed gas through a gas compressor according to the pressure required to form hydrate; and a back pressure subunit, which releases pressure when the pressure of the mixed gas in the intake pipeline exceeds the alarm value.

[0017] Furthermore, in the above technical solution, the internal circulation unit may include a low-concentration storage tank, a second circulation pump, and a hydrate dissolution vessel.

[0018] Furthermore, in the above technical solution, the hydrate dissolution reactor can be equipped with a high-low temperature bath for temperature adjustment, with a working temperature of -20 to 90°C; during the hydration reaction stage of injecting a low-concentration TBAB solution into the reactor cavity, the temperature of the bath can be controlled at the required low temperature; during the hydrate dissolution stage, the temperature of the bath can be controlled at the required high temperature.

[0019] According to a second aspect of the present invention, a method for separating carbon dioxide gas using a hydrate method is provided, comprising the following steps: A) injecting a high-concentration TBAB solution into the inner cavity of a reactor to form type A TBAB hydrate crystals in the inner cavity, wherein the hydrate slurry flows from the inner cavity into the outer cavity and is discharged from the outer cavity for reuse; B) injecting a low-temperature, high-pressure mixed gas containing CO2 into the inner cavity of the reactor; C) injecting a low-concentration TBAB solution into the inner cavity of the reactor to convert type A TBAB hydrate into type B TBAB hydrate, while simultaneously using type A TBAB hydrate crystals as inducing particles to undergo a hydration reaction with the mixed gas in the inner cavity; and after the hydrate slurry dissolves, it captures CO2 while simultaneously discharging the remaining liquid phase for reuse.

[0020] Furthermore, in the above technical solution, the concentration range of the high-concentration TBAB solution in step A can be 20wt%-30wt%; the liquid inlet volume can be 1 / 2 or 2 / 3 of the inner cavity volume; and the inner cavity pressure can be set to atmospheric pressure.

[0021] Furthermore, in the above technical solution, the concentration range of the low-concentration TBAB solution in step C can be 10wt%-15wt%; the liquid inlet volume can be 1 / 2 or 2 / 3 of the inner cavity volume; and the inner cavity pressure can be set to 1-5MPa.

[0022] Furthermore, in the above technical solution, the internal temperature of the reactor can be controlled at a constant temperature between -6℃ and -8℃.

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

[0024] 1) This invention prepares type A TBAB hydrate crystals through an external circulation unit and uses TBAB hydrate crystal nuclei to induce rapid hydrate formation, which can prepare hydrate-induced crystal nuclei under normal pressure and improves hydrate formation efficiency;

[0025] 2) This invention uses a reaction vessel with an inner and outer cavity structure. Through the rotation of the constant temperature layer and the filtration facility at the bottom of the inner cavity, the preparation of induced crystal nuclei and the structural conversion between type A TBAB hydrate and type B TBAB hydrate in a closed space are realized. Type A TBAB hydrate generated in a high-concentration solution is converted into type B TBAB hydrate in a low-concentration solution. The inventors have found that the carbon dioxide storage capacity of the conversion process is higher than that of type B TBAB hydrate alone.

[0026] 3) The system of this invention can shorten the hydrate formation time, improve carbon dioxide storage capacity, and improve separation effect;

[0027] 4) The combined use of the external circulation unit and the internal circulation unit of this invention can ensure the reuse of high / low concentration TBAB solutions respectively. The structure of the reactor cavity and the rotatable constant temperature layer can ensure the effective connection between the internal circulation and external circulation processes. This fully connects the entire process of hydrate formation, gas separation and hydrate dissolution, and realizes the efficient separation of carbon dioxide gas using the hydrate method.

[0028] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, and to make the above and other objects, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the system connection for the continuous separation of carbon dioxide gas using the hydrate method of this invention.

[0030] Figure 2 This is a schematic diagram of the reactor structure in the system of this invention.

[0031] Figure 3-A This is a schematic diagram of the bottom structure of the inner cavity of the reactor of the present invention (showing that the constant temperature layer and the filter hole at the bottom of the cavity are aligned in the first rotation position).

[0032] Figure 3-B This is another structural schematic diagram of the bottom of the reactor cavity of the present invention (showing that the constant temperature layer and the filter hole at the bottom of the cavity are misaligned in the second rotation position).

[0033] Explanation of key figure labels:

[0034] 1-High-pressure gas cylinder; 2-First shut-off valve; 3-Second shut-off valve; 4-Gas compressor; 5-Third shut-off valve; 6-Buffer gas cylinder; 7-Fourth shut-off valve; 8-Fifth shut-off valve; 9-Reaction vessel; 91-Inner cavity; 910-Rotable thermostatic layer; 9100-Thermostatic layer rotating rod; 9101-Bottom filter hole of thermostatic layer; 911-First liquid inlet; 912-Second liquid inlet; 913-Gas inlet; 914-Exhaust port; 915-Bottom filter screen of inner cavity; 9151-Bottom filter hole of inner cavity; 916-Stirring paddle; 9160-Stirring shaft; 917-Inner cavity 92-Outer cavity; 921-Outer cavity outlet; 10-Sixth shut-off valve; 11-Thermostat; 12-Seventh shut-off valve; 13-High concentration storage tank; 14-First circulation pump; 15-Ninth shut-off valve; 16-Hydrate dissolution vessel; 17-Eighth shut-off valve; 18-Third circulation pump; 19-High and low temperature bath; 20-Fourteenth shut-off valve; 21-Eleventh shut-off valve; 22-Back pressure valve; 23-Twelfth shut-off valve; 24-Discharge hose; 25-Low concentration storage tank; 26-Second circulation pump; 27-Thirteenth shut-off valve; 28-Tenth shut-off valve. Detailed Implementation

[0035] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0036] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0037] In this document, for ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “above,” “upper,” etc., are used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that spatial relative terms are intended to encompass different orientations of an object in use or operation, in addition to those depicted in the figures. For example, if an object in the figure is flipped, an element described as “below” or “under” another element or feature would be oriented “above” that element or feature. Thus, the exemplary term “below” can encompass both the downward and upward orientations. An object may also have other orientations (rotated 90 degrees or other orientations), and the spatial relative terms used herein should be interpreted accordingly.

[0038] In this document, the terms "first," "second," etc., are used to distinguish two different elements or parts, and are not used to define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0039] This invention provides a system and method for separating carbon dioxide using a nucleus-induced hydrate method. It is used to separate CO2 / B gas (B gas such as methane). Different gases have different conditions for hydrate formation. When the gas mixture CO2 / B forms hydrates, CO2, which readily forms hydrates, accumulates in the hydrate phase, thus achieving gas separation. This invention shortens the induction time by adding induced nuclei. The process employs a reactor structure with internal and external cavities, enabling a continuous process of introducing induced nuclei and forming hydrates in a closed system. This improves separation efficiency and avoids the energy consumption caused by multi-stage separation methods in existing technologies.

[0040] Through research, the inventors discovered that, in addition to gas molecules, some quaternary ammonium salts can also form hydrates. For example, TBAB can form semi-cage hydrates. TBAB semi-cage hydrates are further divided into type A TBAB·26H2O and type B TBAB·38H2O. The two configurations form different supercages for storing gas molecules, and they can interconvert between each other. It is generally believed that when the mass fraction of TBAB in the solution is higher than 18wt%, the formation of semi-cage hydrates tends towards type A, and vice versa. Type B hydrates are more stable than type A hydrates. Semi-cage hydrates can react with CO2 to form n1CO2·TBAB·26H2O or n2CO2·TBAB·38H2O, where the ideal value of n1 is 1 and the ideal value of n2 is 3. Therefore, type B TBAB hydrates have a stronger CO2 storage capacity than type A TBAB hydrates, and the storage capacity can increase by 277%-367% during the transformation from type A to type B. Based on the above research results, the inventors first generated type A TBAB hydrate in a reactor, used type A TBAB hydrate crystals as inducing particles, and then converted type A TBAB hydrate into type B TBAB hydrate in the same reactor. During the conversion, a full hydration reaction was carried out, thereby separating carbon dioxide gas more effectively.

[0041] Example 1

[0042] like Figure 1 As shown, this embodiment provides a system for separating carbon dioxide gas using a hydrate method, including a reaction vessel 9, an external circulation unit, an inlet unit, and an internal circulation unit. The external circulation unit provides the reaction vessel 9 with a recyclable high-concentration TBAB solution; the inlet unit provides the reaction vessel 9 with a low-temperature, high-pressure mixed gas (containing CO2) suitable for the hydration reaction; the internal circulation unit provides the reaction vessel 9 with a recyclable low-concentration TBAB solution and can dissolve the hydrates after the reaction.

[0043] Further as Figure 2 As shown, the reactor 9 has an inner and outer cavity structure, including an inner cavity 91 and an outer cavity 92. A constant temperature layer 910 is provided on the outer surface of the inner cavity to maintain the temperature required for the hydration reaction. Specifically, the constant temperature layer is rotatable and can be rotated by a constant temperature layer rotating rod located on the upper part of the inner cavity 91. This embodiment has two rotation position points. When the constant temperature layer rotates to the first position (refer to...), Figure 3-A The bottom filter hole 9101 of the constant temperature layer is aligned with the bottom filter hole 9151 of the inner cavity, which is used to discharge the hydrate slurry formed by the external circulation unit to the bottom of the outer cavity 92. At this time, the inner cavity 91 contains only granular type A TBAB hydrate crystals. When the constant temperature layer rotates to the second position (refer to...), Figure 3-BThe filter holes 9101 (dashed line) at the bottom of the isothermal layer and 9151 at the bottom of the inner cavity are offset, making the inner and outer cavities relatively closed. This allows for a thorough hydration reaction after the introduction of a mixed gas and a low-concentration TBAB solution. During both the preparation of type A TBAB hydrate crystals and the hydration reaction using type B TBAB hydrate, the isothermal layer maintains the same temperature, controlled by a thermostat 11. Further details are provided below. Figure 2 As shown, the top of the reactor cavity 91 is provided with a first inlet 911 for receiving a high-concentration TBAB solution, a second inlet 912 for receiving a low-concentration TBAB solution, and an inlet 913 for receiving a low-temperature, high-pressure mixed gas containing CO2. It also has an exhaust port 914 for discharging residual gas after the hydration reaction. Further as... Figure 2 As shown, a stirring paddle 916 is provided at the bottom of the inner cavity 91 of the reactor. A stirring shaft 9160 passes through the inner cavity 91 and the insulation layer 910 and is fixedly connected to the stirring paddle 916. The stirring shaft 9160 can be driven to rotate by a motor (not shown in the figure) and drive the stirring paddle 916 to rotate, which is used to stir the TBAB solution in the inner cavity during the hydration reaction, thereby promoting the hydration reaction and separating the gas. Further as... Figure 2 As shown, the bottom of the outer cavity 92 is provided with an outer cavity outlet 921, and the lower side wall of the inner cavity 91 is provided with an inner cavity outlet 917.

[0044] In this embodiment, the reactor 9 is designed with inner and outer cavities. This not only effectively ensures heat dissipation from the inner cavity, maintains a constant temperature, and reduces energy loss, but also enables the rapid preparation of type A TBAB hydrate crystals by utilizing the rotation of the inner cavity and the alignment and staggering of the bottom filter holes, thus shortening the reaction cycle.

[0045] Further as Figure 1 As shown, in this embodiment, the external circulation unit injects a high-concentration TBAB solution into the inner cavity 91 and forms type A TBAB hydrate crystals in the inner cavity 91. The hydrate slurry flows from the inner cavity 91 into the outer cavity 92 and is discharged from the outer cavity 92 for reuse. Specifically, the external circulation unit includes a high-concentration storage tank 13 and a first circulation pump 14, as well as a sixth shut-off valve 10 and a seventh shut-off valve 12. The required high-concentration TBAB solution is prepared in the high-concentration storage tank 13 and injected into the first inlet 911 of the inner cavity of the reaction vessel 9 through the first circulation pump 14 and the sixth shut-off valve 10. The reacted solution is returned to the high-concentration storage tank 13 through the seventh shut-off valve 12 for concentration adjustment (adjusted to the aforementioned required concentration).

[0046] Further as Figure 1As shown, in this embodiment, the air intake unit injects a low-temperature, high-pressure mixed gas containing CO2 into the inner cavity. Specifically, the air intake unit supplies gas through a high-pressure gas cylinder 1. Since the mixed gas needs to undergo a hydration reaction at a low temperature, cooling can be performed at the front end of the high-pressure gas cylinder or in the air intake pipeline at the rear end of the high-pressure gas cylinder. The cooled mixed gas enters the buffer gas cylinder 6 through parallel air intake pipelines. After obtaining a preset pressure (i.e., the high-pressure environment required for the hydration reaction) in the buffer gas cylinder 6, the mixed gas is injected into the air inlet 913 of the inner cavity of the reactor 9. Specifically, the air intake unit includes a high-pressure gas cylinder 1, a first shut-off valve 2, a second shut-off valve 3, a gas compressor 4, a third shut-off valve 5, and a buffer gas cylinder 6. The gas compressor 4 and the second shut-off valve 3 serve as pressurization subunits, connected in parallel to the air intake pipeline where the third shut-off valve 5 is located. The pressure of the mixed gas is adjusted by the gas compressor 4 according to the pressure required for hydration formation. The buffer gas cylinder 6 supplies gas to the inner cavity 91 of the reactor 9 by controlling the fourth shut-off valve 7 and the fifth shut-off valve 8. The intake unit also includes a back pressure subunit. An eleventh shut-off valve 21 and a back pressure valve 22 are installed on the pipeline between the buffer gas cylinder 6 and the reactor 9. The back pressure valve 22 can release pressure when the pressure of the mixed gas in the intake pipeline exceeds the alarm value. A discharge hose 24 for emergency discharge can also be installed, which is controlled by a twelfth shut-off valve 23.

[0047] Further as Figure 1As shown, in this embodiment, the internal circulation unit injects a low-concentration TBAB solution into the inner cavity 91 of the reaction vessel 9, converting type A TBAB hydrate into type B TBAB hydrate. Simultaneously, type A TBAB hydrate crystals are used as inducing particles to undergo a hydration reaction with the mixed gas in the inner cavity 91. After the reaction, the hydrate slurry is dissolved, CO2 is captured, and the remaining liquid phase is discharged for reuse. Specifically, the internal circulation unit includes a low-concentration storage tank 25, a second circulation pump 26, a hydrate dissolution vessel 16, an eighth shut-off valve 17, a third circulation pump 18, a ninth shut-off valve 15, and a thirteenth shut-off valve 27. The hydrate dissolution vessel 16 is temperature-adjusted and controlled by a high-low temperature bath 19, with an operating temperature of -20 to 90°C, and features overheat protection and overload protection. During the stage of introducing a low-concentration TBAB solution into the reactor cavity, the high-low temperature bath 19 controls the temperature at the low temperature required for the hydration reaction. After the hydration reaction occurs, the hydrate slurry returns to the hydrate dissolution reactor 16, where the high-low temperature bath 19 controls the temperature at the high temperature required for dissolution. The internal circulation unit prepares a low-concentration TBAB solution in the low-concentration storage tank 25, which is injected into the hydrate dissolution reactor 16 through the second circulation pump 26, and then injected into the second inlet 912 of the reactor cavity through the eighth shut-off valve 17 and the third circulation pump 18. The hydrate slurry after the reaction flows out from the outlet 917 of the inner cavity, enters the hydrate dissolution reactor 16 through the ninth shut-off valve 15, and recovers the CO2 released after dissolution through the tenth shut-off valve 28. The dissolved TBAB solution returns to the low-concentration storage tank 25 through the thirteenth shut-off valve 27, is adjusted in concentration, and then recycled.

[0048] This embodiment prepares type A TBAB hydrate crystals through an external circulation unit, employing TBAB hydrate nuclei to induce rapid hydrate formation. This allows for the preparation of hydrate-induced nuclei under normal pressure, improving hydrate formation efficiency. The embodiment utilizes a reactor with internal and external cavities. Through the rotation of the constant temperature layer and the filtration system at the bottom of the internal cavity, it achieves the preparation of induced nuclei within a closed space and the structural conversion between type A and type B TBAB hydrates. Type A TBAB hydrates generated in a high-concentration solution are converted into type B TBAB hydrates in a low-concentration solution. The inventors have discovered that this conversion process significantly affects the formation of type B TBAB hydrates. The storage capacity of carbon dioxide is higher than that of type B TBAB hydrate alone. The system of this embodiment can shorten the hydrate formation time, improve the carbon dioxide storage capacity, and improve the separation effect. The combined use of the external circulation unit and the internal circulation unit can ensure the reuse of high / low concentration TBAB solutions respectively. The structure of the reactor cavity and the rotatable constant temperature layer can ensure the effective connection between the internal circulation and external circulation processes. The system of this embodiment can fully connect the entire process of hydrate formation, gas separation and hydrate decomposition, and can realize the efficient separation of carbon dioxide gas by applying the hydrate method.

[0049] Example 2

[0050] like Figure 1 As shown, this embodiment provides a method for separating carbon dioxide gas using a hydrate method. The method includes the following steps:

[0051] In step S101, a high-concentration TBAB solution is injected into the inner cavity 91 of the reactor, forming type A TBAB hydrate crystals within the cavity. The hydrate slurry flows from the inner cavity into the outer cavity and is then discharged from the outer cavity for reuse. The inventors have discovered that type A TBAB hydrate can be prepared in a TBAB solution with a concentration range of 20wt%-30wt% at a temperature controlled between -6℃ and 8℃. The granular type A TBAB hydrate crystals can promote subsequent hydration reactions through nucleation. Preferably, but not limitingly, the concentration range of the high-concentration TBAB solution in this step can be 20wt%-30wt%; the injection volume can be set to 1 / 2 or 2 / 3 of the inner cavity volume; and the inner cavity pressure can be set to atmospheric pressure.

[0052] Step S102: Inject a low-temperature, high-pressure mixed gas containing CO2 into the inner cavity 91 of the reactor. This low-temperature, high-pressure environment is the temperature and pressure of the mixed gas required for the hydration reaction.

[0053] In step S103, a low-concentration TBAB solution is injected into the inner cavity 91 of the reactor. This converts type A TBAB hydrate into type B TBAB hydrate, while simultaneously using type A TBAB hydrate crystals as inducing particles to undergo a hydration reaction with the mixed gas within the inner cavity 91. After the hydrate slurry dissolves, CO2 is captured, and the remaining liquid phase is discharged for reuse. The inventors have discovered that placing the type A hydrate prepared in step S101 in a 10wt%-15wt% TBAB solution causes it to become unstable at low concentrations and transform into type B hydrate. During this transformation, it can store more CO2. Furthermore, the type A hydrate particles, after the introduction of CO2, act as inducing particles, promoting the rapid formation of CO2 hydrate on its surface, significantly reducing the induction time and achieving rapid separation. Preferably, but not limitingly, the concentration range of the low-concentration TBAB solution in this step is set to 10wt%-15wt%; the liquid inlet volume is also set to 1 / 2 or 2 / 3 of the inner cavity volume; the inner cavity pressure is controlled at 1-5MPa; and the inner cavity temperature of the reactor is the same as in step S101, i.e., controlled at a constant temperature between -6℃ and -8℃.

[0054] The following specific example further illustrates the process method of this embodiment:

[0055] First, a 30wt% TBAB solution is injected into the inner cavity 91 of the reactor through the first inlet 911. The injection volume is half the volume of the reactor. The pressure is atmospheric pressure, and the temperature is controlled at -6.5℃. Under these conditions, type A TBAB hydrate is prepared. After 1 minute, the thermostatic layer 910 is rotated by the thermostatic layer rotating rod 9100 so that the inner cavity filter hole 9151 is aligned and connected with the bottom filter hole 9101 of the thermostatic layer (i.e., the first rotation position). At this time, the solution that has not formed hydrate flows into the outer cavity 92 of the reactor through the evenly distributed round holes at the bottom of the reactor, while the type A TBAB hydrate crystals remain in the inner cavity 91. After the liquid level in the inner cavity reaches 0, the thermostatic layer rotating rod 9100 is rotated back to the thermostatic layer 910 (i.e., the second rotation position) to keep the temperature constant. At this time, the inner and outer cavities are no longer connected.

[0056] Then, a 15wt% TBAB solution enters the reactor cavity 91 through the second inlet 912, filling 2 / 3 of the reactor volume. Simultaneously, the internal gas inlet 913 is opened, introducing CO2 / TBAB gas. The internal pressure can be set to 1-5 MPa, maintaining a constant temperature. After gas introduction, stirring is activated. At a 15wt% concentration, the TBAB solution forms type B TBAB hydrate. Type B TBAB hydrate has a stronger CO2 storage capacity. According to the inventors' research, under the above conditions, the CO2 storage capacity during the conversion of type A hydrate to type B hydrate is approximately 2.77-3.67 times greater. Furthermore, type B TBAB hydrate crystals are more stable than type A TBAB hydrate. Therefore, at a 15wt% concentration, type A TBAB hydrate crystal nuclei not only promote hydrate formation efficiency but also effectively improve CO2 separation during the conversion to type B. After the reaction, the hydrate slurry enters the hydrate dissolving vessel 16 from the inner cavity outlet 917 through the ninth shut-off valve 15. The B gas in the inner cavity is recovered through the fourteenth shut-off valve 20. The hydrate slurry after the reaction is further dissolved in the dissolving vessel 16 and then CO2 is captured and recovered by the tenth shut-off valve 28. At the same time, the remaining liquid phase is discharged and adjusted to the required low concentration for reuse.

[0057] The method in this embodiment corresponds to the system in embodiment 1, and therefore has the same technical effects as in embodiment 1, which will not be repeated here.

[0058] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. Any simple modifications, equivalent changes, and alterations made to the foregoing exemplary embodiments should fall within the scope of protection of the present invention.

Claims

1. A system for separating carbon dioxide gas using a hydrate method, characterized in that, include: The reactor has an internal and external cavity structure, with a constant temperature layer on the outer surface of the inner cavity; An external circulation unit injects a high-concentration TBAB solution into the inner cavity and forms type A TBAB hydrate crystals in the inner cavity. The hydrate slurry flows from the inner cavity into the outer cavity and is discharged from the outer cavity for reuse. The external circulation unit includes a high-concentration storage tank and a first circulation pump. An intake unit that injects a low-temperature, high-pressure mixture of CO2 into the inner cavity; The internal circulation unit injects a low-concentration TBAB solution into the inner cavity, converting type A TBAB hydrate into type B TBAB hydrate. Simultaneously, the type A TBAB hydrate crystals act as inducing particles, reacting with the mixed gas in the inner cavity for hydration. After the hydrate slurry dissolves, CO2 is captured while the remaining liquid phase is discharged for reuse. The internal circulation unit includes a low-concentration storage tank, a second circulation pump, and a hydrate dissolution vessel. The constant temperature layer is rotatable; when the constant temperature layer is rotated to the first position, the bottom filter hole of the constant temperature layer is aligned with the bottom filter hole of the inner cavity, which is used to discharge the hydrate slurry formed by the external circulation unit to the outer cavity; when the constant temperature layer is rotated to the second position, the bottom filter hole of the constant temperature layer is staggered with the bottom filter hole of the inner cavity, so that the inner and outer cavities are relatively closed.

2. The system for separating carbon dioxide gas using the hydrate method according to claim 1, characterized in that, The inner cavity of the reactor is equipped with: The first liquid inlet is used to receive the high-concentration TBAB solution; The second inlet is used to receive the low-concentration TBAB solution; An air inlet is used to receive the low-temperature, high-pressure mixed gas containing CO2; The exhaust port is used to discharge the gas remaining after the hydration reaction.

3. The system for separating carbon dioxide gas using the hydrate method according to claim 1, characterized in that, The bottom of the inner cavity of the reactor is equipped with a stirring paddle, which is connected by a stirring shaft passing through the inner cavity and the insulation layer, and is used to stir the TBAB solution in the inner cavity during the hydration reaction.

4. The system for separating carbon dioxide gas using the hydrate method according to claim 1, characterized in that, The outer cavity has an outer cavity outlet at the bottom; the inner cavity has an inner cavity outlet on the lower side wall.

5. The system for separating carbon dioxide gas using the hydrate method according to claim 1, characterized in that, The filter holes at the bottom of the constant temperature layer and the filter holes at the bottom of the inner cavity are arranged in layers at uniform intervals around the circumference.

6. The system for separating carbon dioxide gas using the hydrate method according to claim 1, characterized in that, The air intake unit supplies air through a high-pressure gas cylinder. The cooled mixed gas enters the buffer gas cylinder through parallel air intake pipelines. After obtaining the mixed gas at a preset pressure in the buffer gas cylinder, it is injected into the inner cavity of the reactor.

7. The system for separating carbon dioxide gas by hydrate method according to claim 6, characterized in that, The intake unit further includes: The booster unit, which is connected in parallel in the intake pipe, adjusts the pressure of the mixture via a gas compressor according to the pressure required to form hydrates. The back pressure subunit releases pressure when the air-fuel mixture pressure in the intake manifold exceeds an alarm value.

8. The system for separating carbon dioxide gas by hydrate method according to claim 1, characterized in that, The hydrate dissolution reactor is equipped with a high-low temperature bath for temperature adjustment, with an operating temperature of -20~90℃. During the hydration reaction stage, when a low-concentration TBAB solution is injected into the reactor cavity, the temperature of the bath is controlled at the required low temperature. During the hydrate dissolution stage, the temperature of the bath is controlled at the required high temperature.

9. A method for separating carbon dioxide gas using a hydrate method, characterized in that, Includes the following steps: A. A high-concentration TBAB solution is injected into the inner cavity of the reactor, and type A TBAB hydrate crystals are formed in the inner cavity. The hydrate slurry flows from the inner cavity into the outer cavity and is discharged from the outer cavity for reuse. B. Inject a low-temperature, high-pressure mixed gas containing CO2 into the inner cavity of the reactor; C. A low-concentration TBAB solution is injected into the inner cavity of the reactor to convert type A TBAB hydrate into type B TBAB hydrate. At the same time, the type A TBAB hydrate crystals are used as inducing particles to carry out a hydration reaction with the mixed gas in the inner cavity. After the hydrate slurry is dissolved, CO2 is captured while the remaining liquid phase is discharged for reuse.

10. The method for separating carbon dioxide gas using the hydrate method according to claim 9, characterized in that, In step A, the concentration range of the high-concentration TBAB solution is 20wt%-30wt%; the liquid inlet volume is 1 / 2 or 2 / 3 of the inner cavity volume, and the inner cavity pressure is atmospheric pressure.

11. The method for separating carbon dioxide gas using the hydrate method according to claim 9, characterized in that, In step C, the concentration range of the low-concentration TBAB solution is 10wt%-15wt%; the liquid inlet volume is 1 / 2 or 2 / 3 of the inner cavity volume, and the inner cavity pressure is 1-5MPa.

12. The method for separating carbon dioxide gas using the hydrate method according to claim 9, characterized in that, The internal temperature of the reactor is controlled at a constant temperature between -6°C and -8°C.

Images