Supercritical carbon dioxide dyeing system and carbon dioxide recovery method thereof

Abstract

The invention provides a supercritical carbon dioxide dyeing system and a carbon dioxide recovery method thereof, and relates to the technical field of dyeing, the supercritical carbon dioxide dyeing system comprises a dyeing kettle, a liquid carbon dioxide storage tank and a buffer tank, a first control valve is arranged between the liquid carbon dioxide storage tank and the dyeing kettle; a second control valve is arranged between the buffer tank and the dyeing kettle, and a third control valve and a compressor are arranged between the buffer tank and the liquid carbon dioxide storage tank. The buffer tank is additionally arranged in the dyeing system, the high-pressure carbon dioxide in the dyeing kettle can be received through the buffer tank, the effect of rapidly releasing the carbon dioxide in the dyeing kettle is achieved, the efficiency of recycling the carbon dioxide in the dyeing kettle can be improved, the waiting time for repeated use of the dyeing kettle is shortened, and then the working efficiency of the dyeing system is improved.

Description

Technical Field

[0001] The invention relates to the technical field of dyeing, in particular to a supercritical carbon dioxide dyeing system and a carbon dioxide recovery method thereof. Background Art

[0002] Supercritical CO2 dyeing, also known as supercritical CO2 dyeing, is an innovative textile dyeing method that uses liquefied CO2 as a dyeing medium. The process involves liquefying CO2 under extreme conditions far exceeding its critical pressure, during which the dye is dissolved and the textile fibers undergo expansion, thereby promoting rapid and uniform penetration of dye molecules. After the dyeing process is completed, the CO2 is volatilized by reducing the pressure, and no washing step is required, demonstrating its unique advantage as an environmentally friendly dyeing process. However, existing waterless CO2 dyeing systems face an efficiency bottleneck: at the end of each dyeing cycle, the residual gaseous CO2 in the system must be completely discharged and recycled. This operation is not only time-consuming, but the existing recovery mechanism is inefficient and can only recover gaseous CO2 on a small scale, which seriously restricts the production efficiency and sustainability of the overall dyeing process. Summary of the invention

[0003] In a first aspect, the present invention provides a supercritical carbon dioxide dyeing system, comprising: a dyeing kettle, a liquid carbon dioxide storage tank and a buffer tank, a first control valve is provided between the liquid carbon dioxide storage tank and the dyeing kettle, a second control valve is provided between the buffer tank and the dyeing kettle, and a third control valve and a compressor are provided between the buffer tank and the liquid carbon dioxide storage tank.

[0004] In an optional embodiment, the volume of the buffer tank is 5 to 25 times the volume of the dyeing kettle.

[0005] In an optional embodiment, the buffer tank is provided with a first cooling device.

[0006] In an optional embodiment, a second cooling device is provided between the liquid carbon dioxide storage tank and the dyeing kettle, and the second cooling device is provided before or at the inlet of the liquid carbon dioxide storage tank.

[0007] In an optional embodiment, the dyeing kettle is provided with an exhaust valve.

[0008] In an optional embodiment, at least two dyeing kettles are provided, each of which is provided with a fourth control valve, and each of which is connected to the first control valve and the second control valve via its own fourth control valve.

[0009] In an optional embodiment, a separation and recovery device is further included, the separation and recovery device is arranged between the dyeing kettle and the liquid carbon dioxide storage tank, and the first control valve is arranged between the separation and recovery device and the dyeing kettle. In a second aspect, the present invention provides a carbon dioxide recovery method for a supercritical carbon dioxide dyeing system, the supercritical carbon dioxide dyeing system comprises a dyeing kettle, a liquid carbon dioxide storage tank and a buffer tank, a first control valve is arranged between the liquid carbon dioxide storage tank and the dyeing kettle, a second control valve is arranged between the buffer tank and the dyeing kettle, and a third control valve and a compressor are arranged between the buffer tank and the liquid carbon dioxide storage tank;

[0010] Before starting to recover carbon dioxide, the first control valve, the second control valve and the third control valve are all in a closed state;

[0011] When recovering carbon dioxide, the following steps are involved:

[0012] Open the first control valve to allow the carbon dioxide in the dyeing kettle to enter the liquid carbon dioxide storage tank through the first control valve;

[0013] Close the first control valve and open the second control valve to allow the carbon dioxide in the dyeing kettle to enter the buffer tank through the second control valve;

[0014] Close the second control valve, open the third control valve and the compressor, and allow the carbon dioxide in the buffer tank to enter the liquid carbon dioxide storage tank through the compressor and the third control valve.

[0015] In an optional embodiment, the supercritical carbon dioxide dyeing system further comprises a separation and recovery device, which is arranged between the dyeing kettle and the liquid carbon dioxide storage tank;

[0016] After the first control valve is opened, the carbon dioxide in the dyeing kettle passes through the first control valve and the separation and recovery device and enters the liquid carbon dioxide storage tank;

[0017] When the pressure in the dyeing kettle and the pressure in the separation and recovery device reach a pressure balance, the first control valve is closed and the second control valve is opened, and the carbon dioxide in the dyeing kettle enters the buffer tank through the second control valve.

[0018] In an optional embodiment, the dyeing kettle is further provided with an exhaust valve. After the second control valve is opened, when the pressure in the dyeing kettle and the pressure in the buffer tank reach a pressure balance, the second control valve is closed, and the exhaust valve, the third control valve and the compressor are opened.

[0019] The supercritical carbon dioxide dyeing system and carbon dioxide recovery method provided by the present invention add a buffer tank in the dyeing system, which can be used to receive the high-pressure carbon dioxide in the dyeing kettle, so as to achieve the effect of quickly releasing the carbon dioxide in the dyeing kettle, and improve the efficiency of recovering the carbon dioxide in the dyeing kettle, thereby reducing the waiting time for the repeated use of the dyeing kettle, and further improving the working efficiency of the dyeing system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of a supercritical carbon dioxide dyeing system provided in an embodiment of the present invention.

[0022] Icons: 100-dyeing kettle; 200-liquid carbon dioxide storage tank; 300-buffer tank; 400-compressor; 500-separation and recovery device; 610-first cooling device; 620-second cooling device; 710-first control valve; 720-second control valve; 730-third control valve; 740-fourth control valve; 750-exhaust valve. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0026] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0027] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0028] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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 mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected 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 the present invention can be understood according to specific circumstances.

[0029] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0030] Embodiment 1

[0031] Embodiment 1 provides a supercritical carbon dioxide dyeing system, such as Figure 1 As shown, it includes: a dyeing kettle 100, a liquid carbon dioxide storage tank 200 and a buffer tank 300, a first control valve 710 is provided between the liquid carbon dioxide storage tank 200 and the dyeing kettle 100, a second control valve 720 is provided between the buffer tank 300 and the dyeing kettle 100, and a third control valve 730 and a compressor 400 are provided between the buffer tank 300 and the liquid carbon dioxide storage tank 200.

[0032] By adding a buffer tank 300 to the dyeing system, the buffer tank 300 can be used to receive the high-pressure carbon dioxide in the dyeing kettle 100, so as to achieve the effect of quickly releasing the carbon dioxide in the dyeing kettle 100, and improve the efficiency of recovering the carbon dioxide in the dyeing kettle 100, thereby reducing the waiting time for the reuse of the dyeing kettle 100, thereby improving the working efficiency of the dyeing system.

[0033] In supercritical carbon dioxide dyeing system, the pressure of dyeing kettle 100 is higher, and the pressure of dyeing kettle 100 can generally reach 15 MPa to 30 MPa, and the pressure of liquid carbon dioxide storage tank 200 is lower, and the pressure of liquid carbon dioxide storage tank 200 can generally reach 2 MPa to 4 MPa.Herein, the explanation for the pressure of dyeing kettle 100 and liquid carbon dioxide storage tank 200 is descriptive rather than for restrictive purpose.Under the state that the first control valve 710 is opened, when dyeing kettle 100 and liquid carbon dioxide storage tank 200 UNICOM, under the effect of pressure difference, the carbon dioxide in the dyeing kettle can flow to liquid carbon dioxide storage tank 200, and this process is the natural recovery process of carbon dioxide.

[0034] In the prior art, in order to improve the recovery efficiency, there is a method of using a compressor 400 to improve the recovery efficiency, including a single compressor 400 and a high-low pressure dual compressor 400, to improve the recovery efficiency of the carbon dioxide in the dyeing kettle to the liquid carbon dioxide storage tank 200. However, due to the large pressure difference between the dyeing kettle 100 and the liquid carbon dioxide storage tank 200, it still takes a long time to complete the recovery operation, and during the recovery operation, the dyeing kettle cannot work, and the dyeing kettle must be reactivated after the carbon dioxide recovery is completed, resulting in a long waiting time for the activation of the dyeing kettle in the supercritical carbon dioxide dyeing system.

[0035] The supercritical carbon dioxide dyeing system provided in the present embodiment is provided with a buffer tank 300 in the dyeing system. When the first control valve 710 is opened, when the dyeing kettle 100 and the liquid carbon dioxide storage tank 200 are connected, the carbon dioxide in the dyeing kettle will flow to the liquid carbon dioxide storage tank 200 under the action of the pressure difference. After the pressure balance is reached, the first control valve 710 is closed and the second control valve 720 is opened, and the buffer tank 300 can be used to receive the remaining high-pressure carbon dioxide in the dyeing kettle 100.

[0036] The buffer tank 300 is in a normal pressure state before receiving the carbon dioxide in the dyeing kettle 100 , and the normal pressure is the local atmospheric pressure.

[0037] The volume of the buffer tank 300 is larger than that of the dyeing kettle 100 but the pressure is lower than that of the dyeing kettle 100 after pressure balance. It can quickly reach pressure balance with the dyeing kettle 100 without setting up the compressor 400. After the dyeing kettle 100 and the buffer tank 300 reach pressure balance, the second control valve 720 is closed. At this time, the pressure of the dyeing kettle 100 is reduced to a lower level, and the dyeing kettle 100 can be reactivated. The carbon dioxide in the buffer tank 300 can enter the liquid carbon dioxide storage tank 200 for further recovery after the compressor 400 and the third control valve 730 are turned on. The recovery time of the carbon dioxide in this step will not occupy the activation time of the dyeing kettle 100, thereby reducing the waiting time for the reuse of the dyeing kettle in the supercritical carbon dioxide dyeing system, thereby improving the working efficiency of the supercritical carbon dioxide dyeing system.

[0038] In an optional embodiment, the volume of the buffer tank 300 is 5 to 25 times the volume of the dyeing kettle 100 .

[0039] The volume of the buffer tank 300 will affect the time for the dyeing kettle 100 and the buffer tank 300 to reach pressure equilibrium and the pressure after pressure equilibrium. Setting the volume of the buffer tank 300 to 5 to 25 times the volume of the dyeing kettle 100 can achieve a balance between the recovery efficiency and the space occupied by the buffer tank 300, which can complete the recovery of carbon dioxide faster without causing the buffer tank 300 to occupy too much space.

[0040] Taking the dyeing kettle 100 with a volume of 1000 liters, a pressure of 5 MPa after reaching pressure balance with the liquid carbon dioxide storage tank 200, and 100 kg of carbon dioxide remaining in the dyeing kettle 100 as an example, when the volume of the buffer tank 300 is 15,000 liters, that is, the volume of the buffer tank 300 is 15 times the volume of the dyeing kettle 100, when the second control valve 720 is opened, the carbon dioxide in the dyeing kettle 100 enters the buffer tank 300 through the second control valve 720. After the pressure in the dyeing kettle 100 and the pressure in the buffer tank 300 reach pressure balance, the pressure in the dyeing kettle 100 is reduced to 0.35 MPa. At this time, 5.6 kg of carbon dioxide remains in the dyeing kettle 100. The remaining carbon dioxide in the dyeing kettle 100 can be directly discharged, with a loss of about 10 yuan, but it can save 10 to 30 minutes of recovery time, that is, it reduces the waiting time required for reactivation of the dyeing kettle 100 by 10 to 30 minutes, thereby improving the efficiency of the supercritical carbon dioxide dyeing system.

[0041] In an optional embodiment, if Figure 1 As shown, the buffer tank 300 is provided with a first cooling device 610 .

[0042] A first cooling device 610 is provided in the buffer tank 300, and the temperature in the buffer tank 300 is lowered by the first cooling device 610, so as to reduce the pressure in the buffer tank 300, so that the buffer tank 300 can receive more carbon dioxide balanced from the dyeing kettle 100 without changing its volume.

[0043] Lowering the temperature in the buffer tank 300 can also lower the air intake temperature before the compression pump so that the operating temperature of the compression pump does not reach an over-temperature state, thereby improving the operating conditions of the compression pump and making the compression pump more durable and long-lasting.

[0044] The specific form of arranging the first cooling device 610 in the buffer tank 300 may be to arrange the condensation pipe in the buffer tank 300, such as Figure 1 As shown, other components and structures of the first cooling device 610 can be arranged outside the buffer tank 300.

[0045] In an optional embodiment, if Figure 1 As shown, a second cooling device 620 is provided between the liquid carbon dioxide storage tank 200 and the dyeing kettle 100 , and the second cooling device 620 is provided before or at the inlet of the liquid carbon dioxide storage tank 200 .

[0046] The second cooling device 620 is provided to reduce the temperature of the carbon dioxide entering the liquid carbon dioxide storage tank 200, so that the pressure in the liquid carbon dioxide storage tank 200 is maintained at a relatively low level, and the relatively low level refers to the low level compared with not providing a cooling device, so that the liquid carbon dioxide storage tank 200 can receive more carbon dioxide balanced from the dyeing kettle 100.

[0047] The second cooling device 620 may be a condenser.

[0048] In an optional embodiment, if Figure 1 As shown, the dyeing kettle 100 is provided with an exhaust valve 750 .

[0049] After the pressure of the dyeing kettle 100 reaches pressure equilibrium with the pressure of the buffer tank 300, the pressure of the dyeing kettle 100 has dropped to a relatively low level. For example, the pressure in the dyeing kettle 100 mentioned in the above embodiment can be reduced to 0.35 MPa, but it is still higher than one atmosphere at this time. The dyeing kettle 100 is provided with an exhaust valve 750, which can discharge the carbon dioxide in the dyeing kettle 100 that has reached pressure equilibrium with the buffer tank 300 and is reduced to a lower pressure but is still higher than the atmospheric pressure. Compared with directly opening the dyeing kettle 100, using the exhaust valve 750 to discharge this part of the carbon dioxide in advance is safer in operation.

[0050] In an optional embodiment, if Figure 1As shown, at least two dyeing kettles 100 are provided, each of which is provided with a fourth control valve 740 , and each of which is connected to the first control valve 710 and the second control valve 720 via its own fourth control valve 740 .

[0051] When multiple dyeing kettles 100 are provided, the multiple dyeing kettles 100 can share the buffer tank 300, the compressor 400 and the liquid carbon dioxide storage tank 200, which can save the space and cost of the buffer tank 300, the compressor 400 and the liquid carbon dioxide storage tank 200. At the same time, the buffer tank 300 can be larger in volume, which is more conducive to the selection of the compressor 400.

[0052] When multiple dyeing kettles 100 are set up, the multiple dyeing kettles 100 can recover carbon dioxide in turn, and the corresponding fourth control valve 740 controls whether the dyeing kettle 100 is connected to the recovery pipeline including the first control valve 710, the second control valve 720, the third control valve 730, the buffer tank 300, the compressor 400 and the liquid carbon dioxide storage tank 200.

[0053] Figure 1 The example in which a supercritical carbon dioxide dyeing system is provided with three dyeing kettles 100 is illustrated. In actual application, a specific number of dyeing kettles 100 may be provided according to requirements.

[0054] In an optional embodiment, if Figure 1 As shown, the supercritical carbon dioxide dyeing system further includes a separation and recovery device 500, which is disposed between the dyeing kettle 100 and the liquid carbon dioxide storage tank 200, and a first control valve 710 is disposed between the separation and recovery device 500 and the dyeing kettle.

[0055] After opening the first control valve 710, the high-pressure carbon dioxide in the dyeing kettle enters the liquid carbon dioxide storage tank 200 again through the separation recovery device 500. The separation recovery device 500 can play the effect of filtering the carbon dioxide from the dyeing kettle. The pressure in the separation recovery device 500 can be higher than the pressure of the liquid carbon dioxide storage tank 200, or the pressure in the separation recovery device 500 can reach the maximum pressure of the liquid carbon dioxide storage tank 200, for example, the pressure of the liquid carbon dioxide storage tank 200 is 2 MPa to 4 MPa, and the pressure of the separation recovery device 500 can reach 4 MPa. When opening the first control valve 710, the dyeing kettle reaches pressure balance with the separation recovery device 500, and the dyeing kettle no longer needs to reach balance with the pressure of the liquid carbon dioxide storage tank 200, thereby can reach pressure balance faster, complete the natural recovery stage faster.

[0056] When a second cooling device 620 is also provided, Figure 1As shown, the second cooling device 620 is disposed between the separation and recovery device 500 and the liquid carbon dioxide storage tank 200 .

[0057] Embodiment 2

[0058] Embodiment 2 provides a carbon dioxide recovery method for a supercritical carbon dioxide dyeing system. The supercritical carbon dioxide dyeing system includes a dyeing kettle 100, a liquid carbon dioxide storage tank 200 and a buffer tank 300, a first control valve 710 is provided between the liquid carbon dioxide storage tank 200 and the dyeing kettle 100, a second control valve 720 is provided between the buffer tank 300 and the dyeing kettle 100, and a third control valve 730 and a compressor 400 are provided between the buffer tank 300 and the liquid carbon dioxide storage tank 200.

[0059] Before starting to recover carbon dioxide, the first control valve 710, the second control valve 720 and the third control valve 730 are all in a closed state;

[0060] When recovering carbon dioxide, the following steps are involved:

[0061] Open the first control valve 710 to allow the carbon dioxide in the dyeing kettle 100 to enter the liquid carbon dioxide storage tank 200 through the first control valve 710;

[0062] The first control valve 710 is closed, and the second control valve 720 is opened, so that the carbon dioxide in the dyeing kettle 100 enters the buffer tank 300 through the second control valve 720;

[0063] The second control valve 720 is closed, and the third control valve 730 and the compressor 400 are opened, so that the carbon dioxide in the buffer tank 300 enters the liquid carbon dioxide storage tank 200 through the compressor 400 and the third control valve 730 .

[0064] After closing the second control valve 720 , the dyeing kettle 100 can be reactivated, and the process of the carbon dioxide in the buffer tank 300 passing through the compressor 400 and the third control valve 730 and entering the liquid carbon dioxide storage tank 200 does not affect the use of the dyeing kettle 100 .

[0065] After the compressor 400 is turned on, and after the compressor 400 compresses all the gas in the buffer tank 300 into the liquid carbon dioxide storage tank 200, the compressor 400 is turned off to complete the recovery process of all carbon dioxide.

[0066] In an optional embodiment, the supercritical carbon dioxide dyeing system further includes a separation and recovery device 500, which is disposed between the dyeing kettle 100 and the liquid carbon dioxide storage tank 200;

[0067] After the first control valve 710 is opened, the carbon dioxide in the dyeing kettle 100 passes through the first control valve 710 and the separation and recovery device 500 and enters the liquid carbon dioxide storage tank 200;

[0068] When the pressure in the dyeing kettle 100 and the pressure in the separation recovery device 500 reach a pressure balance, the first control valve 710 is closed, the second control valve 720 is opened, and the carbon dioxide in the dyeing kettle 100 enters the buffer tank 300 through the second control valve 720 .

[0069] In an optional embodiment, the dyeing kettle 100 is further provided with an exhaust valve 750. After the second control valve 720 is opened, when the pressure in the dyeing kettle 100 and the pressure in the buffer tank 300 reach a pressure balance, the second control valve 720 is closed, and the exhaust valve 750, the third control valve 730 and the compressor 400 are opened.

[0070] After the exhaust valve 750 is opened, the dyeing kettle 100 is reopened until the pressure in the dyeing kettle 100 drops to normal pressure.

[0071] In an optional embodiment, when a plurality of dyeing kettles 100 are provided, the carbon dioxide in the plurality of dyeing kettles 100 is recovered sequentially.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A supercritical carbon dioxide dyeing system, characterized in that: include: A dyeing kettle (100), a liquid carbon dioxide storage tank (200) and a buffer tank (300), wherein a first control valve (710) is provided between the liquid carbon dioxide storage tank (200) and the dyeing kettle (100), a second control valve (720) is provided between the buffer tank (300) and the dyeing kettle (100), and a third control valve (730) and a compressor (400) are provided between the buffer tank (300) and the liquid carbon dioxide storage tank (200).

2. The supercritical carbon dioxide dyeing system according to claim 1, characterized in that: The volume of the buffer tank (300) is 5 to 25 times the volume of the dyeing kettle (100).

3. The supercritical carbon dioxide dyeing system according to claim 1, characterized in that: The buffer tank (300) is provided with a first temperature reduction device (610).

4. The supercritical carbon dioxide dyeing system according to claim 1, characterized in that: A second cooling device (620) is provided between the liquid carbon dioxide storage tank (200) and the dyeing kettle (100), and the second cooling device (620) is provided before or at the inlet of the liquid carbon dioxide storage tank (200).

5. The supercritical carbon dioxide dyeing system according to claim 1, characterized in that: The dyeing kettle (100) is provided with an exhaust valve (750).

6. The supercritical carbon dioxide dyeing system according to claim 1, characterized in that: At least two dyeing kettles (100) are provided, each of which is provided with a fourth control valve (740), and each of which is connected to the first control valve (710) and the second control valve (720) via its own fourth control valve (740).

7. The supercritical carbon dioxide dyeing system according to claim 6, characterized in that: It also includes a separation and recovery device (500), which is arranged between the dyeing kettle (100) and the liquid carbon dioxide storage tank (200), and a first control valve (710) is arranged between the separation and recovery device (500) and the dyeing kettle (100).

8. A method for recovering carbon dioxide in a supercritical carbon dioxide dyeing system, characterized in that: The supercritical carbon dioxide dyeing system comprises a dyeing kettle (100), a liquid carbon dioxide storage tank (200) and a buffer tank (300); a first control valve (710) is provided between the liquid carbon dioxide storage tank (200) and the dyeing kettle (100); a second control valve (720) is provided between the buffer tank (300) and the dyeing kettle (100); and a third control valve (730) and a compressor (400) are provided between the buffer tank (300) and the liquid carbon dioxide storage tank (200); Before starting to recover carbon dioxide, the first control valve (710), the second control valve (720) and the third control valve (730) are all in a closed state; When recovering carbon dioxide, the following steps are involved: Opening the first control valve (710) to allow the carbon dioxide in the dyeing kettle (100) to enter the liquid carbon dioxide storage tank (200) through the first control valve (710); The first control valve (710) is closed, and the second control valve (720) is opened, so that the carbon dioxide in the dyeing kettle (100) enters the buffer tank (300) through the second control valve (720); The second control valve (720) is closed, and the third control valve (730) and the compressor (400) are opened, so that the carbon dioxide in the buffer tank (300) passes through the compressor (400) and the third control valve (730) and enters the liquid carbon dioxide storage tank (200).

9. The carbon dioxide recovery method of the supercritical carbon dioxide dyeing system according to claim 8, characterized in that: The supercritical carbon dioxide dyeing system further comprises a separation and recovery device (500), wherein the separation and recovery device (500) is arranged between the dyeing kettle (100) and the liquid carbon dioxide storage tank (200); After the first control valve (710) is opened, the carbon dioxide in the dyeing kettle (100) passes through the first control valve (710) and the separation and recovery device (500) and enters the liquid carbon dioxide storage tank (200); When the pressure in the dyeing kettle (100) and the pressure in the separation and recovery device (500) reach a pressure balance, the first control valve (710) is closed, the second control valve (720) is opened, and the carbon dioxide in the dyeing kettle (100) enters the buffer tank (300) through the second control valve (720).

10. The method for recovering carbon dioxide in a supercritical carbon dioxide dyeing system according to claim 8, characterized in that: The dyeing kettle (100) is further provided with an exhaust valve (750). After the second control valve (720) is opened, when the pressure in the dyeing kettle (100) and the pressure in the buffer tank (300) reach a pressure balance, the second control valve (720) is closed, and the exhaust valve (750), the third control valve (730) and the compressor (400) are opened.

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