Collecting device

Abstract

The present application relates to a collection device for purifying to recover carbon dioxide, the collection device comprising: a pretreatment mechanism for pretreating a raw gas to form a pretreated gas; a first recovery mechanism comprising a first separation column for separating a high-boiling-point component having a higher boiling point than carbon dioxide in the pretreated gas, so as to convert the pretreated gas into an intermediate-treated gas; and a second recovery mechanism comprising a second separation column for separating a low-boiling-point component having a lower boiling point than carbon dioxide in the intermediate-treated gas, so as to convert the intermediate-treated gas into liquid carbon dioxide. In view of the fact that the high-boiling-point component contains water and sulfur-containing substances, the high-boiling-point component and the intermediate-treated gas containing carbon dioxide can be effectively separated in the first separation column, that is, the water and sulfur-containing substances can be separated and removed by the same mechanism, so that the purification and recovery process of carbon dioxide is simplified, and the collection device is more simple in structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the chemical technology field, in particular to a collecting device. BACKGROUND

[0002] Carbon dioxide, as one of the main components of global greenhouse gases, has an increasingly large emission, which has a great influence on the global climate change. At the same time, carbon dioxide, as an important resource, has a wide range of uses, such as refrigerant, food additive, fire extinguishing agent, gas protection agent, chemical raw material, oil and gas exploitation, agricultural production, etc. If carbon dioxide is recycled, stored and applied, not only the utilization of carbon resources is improved, but also the emission of greenhouse gases is reduced.

[0003] At present, the main methods for recovering carbon dioxide include chemical absorption method, pressure swing adsorption method, membrane separation method and low-temperature separation method as well as the combination application of these methods. The carbon dioxide products obtained by the chemical absorption method, the pressure swing adsorption method and the membrane separation method have low purity and are in gaseous state, which is not conducive to storage and transportation; the low-temperature method can obtain high-purity liquid carbon dioxide, which is stored in low-temperature tanks and transported by tank cars. However, the collecting device used for performing the low-temperature method usually has the defect of complex structure. SUMMARY

[0004] The present application solves one technical problem of how to simplify the structure of the collecting device.

[0005] A collecting device for purifying to recover carbon dioxide, the collecting device comprising:

[0006] a pretreatment mechanism for pretreating a raw gas to form a pretreated gas;

[0007] a first recovery mechanism comprising a first separation tower for separating a high-boiling-point component having a boiling point higher than that of carbon dioxide in the pretreated gas, so as to convert the pretreated gas into an intermediate treated gas; and

[0008] a second recovery mechanism comprising a second separation tower for separating a low-boiling-point component having a boiling point lower than that of carbon dioxide in the intermediate treated gas, so as to convert the intermediate treated gas into liquid carbon dioxide.

[0009] In one of the embodiments, the first recovery mechanism further comprises a first reboiler and a first reboiling separator, the first reboiler is used to provide heat to the first separation tower, the high-boiling-point component enters into the first reboiling separator after being heated by the first reboiler, the first reboiling separator is used to perform gas-liquid separation on the high-boiling-point component, and the gas separated from the high-boiling-point component returns to the first separation tower.

[0010] In one of the embodiments, the first recovery mechanism further comprises a first condenser and a first condensing separator, the intermediate treatment gas is cooled by the first condenser and then enters the first condensing separator, the first condensing separator is used for gas-liquid separation of the intermediate treatment gas, the gas separated from the intermediate treatment gas enters the second separation tower, and the liquid separated from the intermediate treatment gas returns to the first separation tower.

[0011] In one of the embodiments, the second recovery mechanism further comprises a second reboiler and a second reboiling separator, the second reboiler is used for providing heat to the second separation tower, the intermediate treatment gas is converted into end treatment components after removing low-boiling components in the second separation tower, the end treatment components are heated by the second reboiler and then enter the second reboiling separator, the second reboiling separator is used for gas-liquid separation of the end treatment components, the liquid separated from the end treatment components is liquid carbon dioxide, and the gas separated from the end treatment components returns to the second separation tower.

[0012] In one of the embodiments, the second recovery mechanism further comprises a second condenser and a second condensing separator, the low-boiling components are cooled by the second condenser and then enter the second condensing separator, and the second condensing separator is used for gas-liquid separation of the low-boiling components, and the liquid separated from the low-boiling components returns to the second separation tower.

[0013] In one of the embodiments, the second recovery mechanism further comprises a throttle valve, the gas separated from the low-boiling components is cooled by the throttle valve and then enters the second condenser for heat exchange.

[0014] In one of the embodiments, the gas separated from the low-boiling components enters the pretreatment mechanism for heat exchange after the second condenser.

[0015] In one of the embodiments, an evaporation supercooler is further included, the liquid carbon dioxide converted from the intermediate treatment gas is cooled by the evaporation supercooler and then recovered, and the intermediate treatment gas discharged from the first separation tower is cooled by the evaporation supercooler and then enters the second separation tower.

[0016] In one of the embodiments, a refrigeration mechanism is further included, the refrigeration mechanism is used for providing heat and cold to the first separation tower, and the refrigeration mechanism is also used for providing heat to the second separation tower.

[0017] In one of the embodiments, the pre-treatment mechanism comprises a filter, a compressor and a pre-cooler, the filter is used to filter the raw gas to be input into the compressor, the compressor is used to pressurize the raw gas to be input into the pre-cooler, and the pre-cooler is used to cool the raw gas to be input into the first separation tower.

[0018] One of the technical effects of one of the embodiments of the present application is that, through the action of the first separation tower, the high-boiling-point components with a boiling point higher than carbon dioxide in the pre-processed gas are separated, so that the pre-processed gas from which the high-boiling-point components with a boiling point higher than carbon dioxide have been separated is converted into intermediate-processed gas, and through the action of the second separation tower, the low-boiling-point components with a boiling point lower than carbon dioxide in the intermediate-processed gas are separated, so that the intermediate-processed gas is finally converted into liquid carbon dioxide. In view of the fact that the high-boiling-point components include water and sulfur-containing substances, the high-boiling-point components and the intermediate-processed gas containing carbon dioxide can be effectively separated in the first separation tower, that is, the water and sulfur-containing substances can be separated and removed through the same mechanism, so that the purification and recovery process of carbon dioxide is simplified, the recovery efficiency of carbon dioxide is improved, and thus the collecting device is simpler in structure, which is also conducive to reducing the manufacturing cost of the collecting device and the collection cost of carbon dioxide. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A plan view of the collecting device provided by one of the embodiments is shown. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0021] In the description of the present application, it should be understood that if these terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0022] In addition, the terms "first", "second", and the like, if any appear in the description, are used for descriptive purposes and are not to be construed as indicating or implying relative importance or an indicated number of technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, if the term "a plurality of" appears, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0023] In the present application, unless otherwise explicitly specified and limited, if the terms "mounting", "connecting", "connecting", "fixing" and the like appear, these terms should be interpreted broadly. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0024] In the present application, unless otherwise explicitly specified and limited, if the first feature is described as "on" or "under" the second feature, etc., it can mean that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the second feature, or only indicate that the first feature is higher than the second feature in horizontal height. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the second feature, or only indicate that the first feature is lower than the second feature in horizontal height.

[0025] It should be noted that if an element is referred to as "fixed to" or "provided on" another element, it can be directly on another element or there can be a middle element. If an element is considered to be "connected" to another element, it can be directly connected to another element or there can be a middle element. If present, the terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used in the present application are for illustrative purposes only and do not represent the only implementation.

[0026] Referring to Figure 1 An embodiment of the present application provides a collection device 10 for purifying a raw gas 110 such as flue gas or chemical tail gas rich in carbon dioxide gas, thereby recovering carbon dioxide in the raw gas 110. Generally, the volume percentage of carbon dioxide in the raw gas 110 can be more than 60%. The collection device 10 includes a pretreatment mechanism 200, a first recovery mechanism 300, and a second recovery mechanism 400.

[0027] In some embodiments, the pretreatment mechanism 200 is configured to pretreat the raw gas 110 to form a pretreated gas 120. The pretreatment mechanism 200 can include a filter 210, a compressor 220, and a pre-cooler 230. The raw gas 110 is first introduced into the filter 210, which is configured to filter the raw gas 110 to remove free water and solid impurities in the raw gas 110. The raw gas 110 from which the free water and solid impurities have been removed is then introduced into the compressor 220, which is configured to pressurize the raw gas 110 such that the pressure of the raw gas 110 can reach 2.0 MPaG to 6.0 MPaG. The condensate generated by the compression of the raw gas 110 in the compressor 220 can be discharged to the outside. The pressurized raw gas 110 is then introduced into the pre-cooler 230, which is configured to cool the raw gas 110 to reduce the temperature of the raw gas 110. Thus, by pressurizing and cooling the raw gas 110, some components in the raw gas 110 can be quickly liquefied in the subsequent treatment process. The gas output from the pre-cooler 230 is the pretreated gas 120.

[0028] In some embodiments, the first recovery mechanism 300 includes a first separation column 310, a first reboiler 320, a first reboiler separator 330, a first condenser 340, and a first condenser separator 350. The first separation column 310 can be understood as a heavy component removal column. The pretreated gas 120 output from the pretreatment mechanism 200 can be introduced into the first separation column 310 from the bottom, so as to separate the high-boiling-point components 140 having a boiling point higher than carbon dioxide from the pretreated gas 120, so that the pretreated gas 120 from which the high-boiling-point components 140 have been separated is converted into an intermediate treatment gas 130. Specifically, when the pretreated gas 120 enters the first separation column 310, the temperature in the first separation column 310 is relatively low, and the components in the pretreated gas 120 having a relatively high boiling point are easily liquefied. The first reboiler 320 is configured to heat the first separation column 310, so that carbon dioxide and components having a boiling point lower than carbon dioxide mainly form the gaseous intermediate treatment gas 130, and components having a boiling point higher than carbon dioxide mainly form the liquid high-boiling-point components 140.

[0029] Since the gaseous intermediate treatment gas 130 is located above the liquid high-boiling-point component 140, the gaseous intermediate treatment gas 130 will be discharged from the top of the first separation tower 310, and the liquid high-boiling-point component 140 will be discharged from the bottom of the first separation tower 310. The high-boiling-point component 140 discharged from the bottom will first be input to the first reboiler 320 to be heated; the heated high-boiling-point component 140 will enter the first reboiling separator 330, which is used to separate the high-boiling-point component 140 into liquid and gas, so that the high-boiling-point component 140 is separated into two parts. The gas separated from the high-boiling-point component 140 will be returned to the first separation tower 310. Since the gas separated from the high-boiling-point component 140 can contain carbon dioxide, the gas separated from the high-boiling-point component 140 can be separated again in the first separation tower 310, so as to improve the recovery rate of carbon dioxide. The liquid separated from the high-boiling-point component 140 is discharged to the outside. In fact, the liquid separated from the high-boiling-point component 140 contains a large amount of water, sulfur-containing substances, and methanol, and the sulfur-containing substances include hydrogen sulfide.

[0030] If the collecting device 10 uses different mechanisms to separate and remove water and sulfur-containing substances in the raw gas 110, for example, a molecular sieve dehydration mechanism is used to separate and remove water in the raw gas 110, and a dry desulfurization mechanism is used to separate and remove sulfur-containing substances in the raw gas 110. This will make the carbon dioxide purification and recovery process more complex, reduce the carbon dioxide recovery efficiency, and then lead to a more complex structure of the entire collecting device 10, increasing the manufacturing cost of the collecting device 10 and the carbon dioxide collection cost.

[0031] For the collecting device 10 in the above embodiment, since the high-boiling-point component 140 contains water and sulfur-containing substances, the high-boiling-point component 140 and the intermediate treatment gas 130 containing carbon dioxide can be effectively separated in the first separation tower 310, that is, water and sulfur-containing substances can be separated and removed by the same mechanism, which will simplify the carbon dioxide purification and recovery process, improve the carbon dioxide recovery efficiency, and thus make the structure of the collecting device 10 simpler, which is also conducive to reducing the manufacturing cost of the collecting device 10 and the carbon dioxide collection cost.

[0032] In some embodiments, the intermediate treated gas 130 is subjected to heat exchange by the first condenser 340, such that the first condenser 340 cools the intermediate treated gas 130. The intermediate treated gas 130 cooled by the first condenser 340 is input into the first condensing separator 350, which separates the intermediate treated gas 130 into liquid and gas, and the gas separated from the intermediate treated gas 130 is input into the second recovery mechanism 400, and the liquid separated from the intermediate treated gas 130 is returned to the first separation tower 310. Since the temperature of the liquid separated from the intermediate treated gas 130 is low, which can be not higher than -14°C, the liquid separated from the intermediate treated gas 130 will deliver cold energy to the first separation tower 310, so that part of the cost of the pre-treated gas 120 input into the first separation tower 310 can be effectively liquefied. It can be understood that the liquid separated from the intermediate treated gas 130 can be input into the first separation tower 310 from the top of the tower in the form of spraying, and since the pre-treated gas 120 is input into the first separation tower 310 from the bottom of the tower, the liquid separated from the intermediate treated gas 130 is in full contact with the pre-treated gas 120 during the upward movement of the pre-treated gas 120 from the bottom of the tower, so that the high-boiling-point component 140 in the intermediate treated gas 130 can be liquefied.

[0033] In some embodiments, the collection device 10 further comprises an evaporation supercooler 500, and the gas separated from the intermediate treated gas 130 can first enter the evaporation supercooler 500 to be subjected to heat exchange, so that the gas separated from the intermediate treated gas 130 is cooled before being input into the second recovery mechanism 400, so as to create favorable conditions for the gas separated from the intermediate treated gas 130 to be liquefied in the second recovery mechanism 400. After passing through the evaporation supercooler 500, the gas separated from the intermediate treated gas 130 can also be cooled by a throttling element before being input into the second recovery mechanism 400.

[0034] In some embodiments, the second recovery mechanism 400 comprises a second separation column 410, a second reboiler 420, a second reboil separator 430, a second condenser 440 and a second condensate separator 450. The second separation column 410 can be a light-removal column. The intermediate treatment gas 130 outputted from the first separation column 310 can be inputted into the second separation column 410 from the top of the column, so as to separate the low-boiling-point components 131 having a lower boiling point than carbon dioxide in the intermediate treatment gas 130, so that the intermediate treatment gas 130 from which the low-boiling-point components 131 have been separated becomes the end treatment component 132. Specifically, when the intermediate treatment gas 130 is inputted into the second separation column 410, the temperature in the second separation column 410 is relatively low, and the intermediate treatment gas 130 can be liquefied. The second reboiler 420 is used to heat the second separation column 410, so that the components having a lower boiling point than carbon dioxide mainly form the low-boiling-point components 131 in a gaseous state, which can be understood as non-condensable gas components such as light hydrocarbons, nitrogen and hydrogen, and the components rich in carbon dioxide mainly form the end treatment component 132 in a liquid state.

[0035] Since the low-boiling-point components 131 in a gaseous state are located above the end treatment component 132 in a liquid state, the low-boiling-point components 131 in a gaseous state are discharged from the top of the second separation column 410, and the end treatment component 132 in a liquid state is discharged from the bottom of the second separation column 410. The end treatment component 132 discharged from the bottom is first inputted into the second reboiler 420 for heating; the end treatment component 132 after being heated is inputted into the second reboil separator 430, which is used to separate the end treatment component 132 into a liquid and a gas, so as to separate the end treatment component 132 into two parts. The gas separated from the end treatment component 132 is returned to the second separation column 410. Since the gas separated from the end treatment component 132 can contain carbon dioxide, the gas separated from the end treatment component 132 can be further separated in the second separation column 410, so as to improve the recovery rate of carbon dioxide. The liquid separated from the end treatment component 132 is liquid carbon dioxide with a high purity. The liquid carbon dioxide is subjected to heat exchange in the evaporative supercooler 500, so as to be further cooled to a temperature of about -22°C, and finally stored in the storage tank 700.

[0036] In some embodiments, the low-boiling-point component 131 is subjected to heat exchange by the second condenser 440, such that the second condenser 440 cools the low-boiling-point component 131. The low-boiling-point component 131 cooled by the second condenser 440 is input into the second condensing separator 450, which is used to separate the low-boiling-point component 131 into liquid and gas, such that the gas separated from the low-boiling-point component 131 is discharged to the outside, and the liquid separated from the low-boiling-point component 131 is returned to the first separation tower 310. Since the temperature of the liquid separated from the low-boiling-point component 131 is low, the liquid separated from the low-boiling-point component 131 can deliver cold energy to the second separation tower 410, so as to effectively liquefy the end-treatment component 132 in the intermediate treatment gas 130 input into the second separation tower 410. It can be understood that the liquid separated from the low-boiling-point component 131 can be input into the second separation tower 410 from the top down in the form of spraying, so as to sufficiently contact the intermediate treatment gas 130 with the liquid separated from the low-boiling-point component 131 to cool the intermediate treatment gas 130, so as to liquefy the end-treatment component 132 in the intermediate treatment gas 130.

[0037] In some embodiments, the second recovery mechanism 400 further comprises a throttle valve 460, and the gas separated from the low-boiling-point component 131 first passes through the throttle valve 460, which cools the gas. The cooled gas is input into the second condenser 440 for heat exchange, so that the low-boiling-point component 131 from the second separation tower 410 into the second condenser 440 is cooled by heat absorption. It can be understood that the gas separated from the low-boiling-point component 131 can deliver cold energy to the second condenser 440 and the second separation tower 410. In this way, the second separation tower 410 can be delivered with cold energy without setting an additional chiller, further simplifying the structure of the collection device 10.

[0038] When the gas separated from the low-boiling-point component 131 passes through the second condenser 440, it can be further input into the pre-cooler 230 for heat exchange, so that the gas separated from the low-boiling-point component 131 further absorbs the heat of the raw material gas 110, and then the raw material gas 110 is cooled. It can be understood that the gas separated from the low-boiling-point component 131 can provide cold energy for the pre-cooler 230, avoiding the delivery of cold energy to the pre-cooler 230 by setting an additional chiller, further simplifying the structure of the collection device 10. When the gas separated from the low-boiling-point component 131 passes through the pre-cooler 230 for heat exchange, it can be discharged to the outside.

[0039] In some embodiments, the collecting device 10 further comprises a refrigeration mechanism 600 for providing heat and cold to the first separation tower 310, and for providing heat to the second separation tower 410. The refrigeration mechanism 600 can use one or several combinations of propane, propylene, ethylene, etc. as refrigerant. The refrigerant outputted by the refrigeration mechanism 600 can be divided into two paths, for the sake of description, the two paths of refrigerant are respectively denoted as first path refrigerant 151 and second path refrigerant 152. The first path refrigerant 151 passes through the first reboiler 320 to provide heat to the first separation tower 310. The first path refrigerant 151 passing through the first reboiler 320 can also be cooled by a throttling element and then enter the first condenser 340 to provide cold to the first condenser 340 and the first separation tower 310. The first path refrigerant 151 passing through the first condenser 340 will return to the refrigeration mechanism 600 to exchange heat, thereby creating conditions for the next cycle. The second path refrigerant 152 passes through the second reboiler 420 to provide heat to the second separation tower 410. The second path refrigerant 152 passing through the second reboiler 420 will pass through the evaporative supercooler 500 to absorb heat, so as to cool the intermediate processing gas 130 and liquid carbon dioxide flowing through the evaporative supercooler 500. The second path refrigerant 152 passing through the evaporative supercooler 500 will return to the refrigeration mechanism 600 to exchange heat, thereby creating conditions for the next cycle.

[0040] The technical features of the above-mentioned embodiments can be combined in any manner. For the sake of brevity, not all possible combinations of the technical features in the above-mentioned embodiments are described, however, as long as the combinations of the technical features do not contradict each other, they should be considered within the scope of the present disclosure.

[0041] The above-mentioned embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent scope of the application. It should be pointed out that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A collection device for purifying to recover carbon dioxide, characterized by, The collecting device comprises: a pretreatment mechanism for pretreating the raw gas to form a pretreated gas; a first recovery mechanism comprising a first separation tower for separating high-boiling-point components with a boiling point higher than carbon dioxide in the pretreated gas, so that the pretreated gas is converted into an intermediate treatment gas; the first recovery mechanism further comprises a first reboiler and a first reboiling separator, the first reboiler is used to provide heat for the first separation tower, the high-boiling-point components enter the first reboiling separator after being heated by the first reboiler, and the first reboiling separator is used for gas-liquid separation of the high-boiling-point components, and the gas separated from the high-boiling-point components returns to the first separation tower; a second recovery mechanism comprising a second separation tower for separating low-boiling-point components with a boiling point lower than carbon dioxide in the intermediate treatment gas, so that the intermediate treatment gas is converted into liquid carbon dioxide; the second recovery mechanism further comprises a second reboiler and a second reboiling separator, the second reboiler is used to provide heat for the second separation tower, the intermediate treatment gas is converted into an end treatment component after removing the low-boiling-point components in the second separation tower, the end treatment component enters the second reboiling separator after being heated by the second reboiler, and the second reboiling separator is used for gas-liquid separation of the end treatment component, the liquid separated from the end treatment component is the liquid carbon dioxide, and the gas separated from the end treatment component returns to the second separation tower; further comprising an evaporation subcooler, the liquid carbon dioxide converted from the intermediate treatment gas is cooled by the evaporation subcooler and recovered; the intermediate treatment gas discharged from the first separation tower is cooled by the evaporation subcooler and enters the second separation tower.

2. The collection device of claim 1, wherein, The liquid separated from the intermediate treatment gas can be input into the first separation tower from top to bottom in a spraying manner.

3. The collection device of claim 1, wherein, The first recovery mechanism further comprises a first condenser and a first condensing separator, the intermediate treatment gas enters the first condensing separator after being cooled by the first condenser, and the first condensing separator is used for gas-liquid separation of the intermediate treatment gas, the gas separated from the intermediate treatment gas enters the second separation tower, and the liquid separated from the intermediate treatment gas returns to the first separation tower.

4. The collection device of claim 1, wherein, The second recovery mechanism further comprises a second condenser and a second condensing separator, the low-boiling-point components enter the second condensing separator after being cooled by the second condenser, and the second condensing separator is used for gas-liquid separation of the low-boiling-point components, and the liquid separated from the low-boiling-point components returns to the second separation tower.

5. The collection device of claim 4, wherein, The second recovery mechanism further comprises a throttle valve, the gas separated from the low-boiling-point components enters the second condenser for heat exchange after being cooled by the throttle valve.

6. The collection device of claim 5, wherein, The gas separated from the low-boiling-point components enters the pretreatment mechanism for heat exchange after passing through the second condenser.

7. The collection device of claim 1, wherein, Also included is a refrigeration mechanism for providing heat and cold to the first separation tower, and for providing heat to the second separation tower.

8. The collection device of claim 7, wherein, The refrigerant output by the refrigeration mechanism is divided into two paths, a first path is throttled after being heated by the first reboiler, and then enters a first condenser to be cooled; a second path enters the evaporative supercooler to be cooled after being heated by the second reboiler, and returns to the refrigeration mechanism after completing heat exchange.

9. The collection device of any one of claims 1 to 8, wherein, The pretreatment mechanism includes a filter, a compressor, and a precooler, the filter is used to filter raw gas to be input to the compressor, the compressor is used to pressurize the raw gas to be input to the precooler, and the precooler is used to cool the raw gas to be input to the first separation tower.

10. The collection device of claim 9, wherein, The filter is used to eliminate free water and solid impurities in the raw gas.

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