Carbon dioxide trapping device based on membrane separation low-temperature condensation process

Abstract

The utility model provides a carbon dioxide trapping device based on a membrane separation low-temperature condensation process, which overcomes the defects of low carbon dioxide purity and low trapping efficiency in the existing carbon dioxide low-temperature condensation technology. The device comprises a pretreatment unit, a membrane separation unit, a liquefaction unit, a solidification unit and a storage tank, the pretreatment unit is used for removing impurities in flue gas, and a flue gas inlet and a flue gas outlet are formed in the pretreatment unit; activated carbon can be used as an adsorbent in the pretreatment unit; the membrane separation unit is used for capturing carbon dioxide in the pretreated flue gas and comprises a first-stage membrane separation assembly, a second-stage membrane separation assembly and a pressure gauge; the concentration of captured carbon dioxide can be effectively improved by adopting a multi-stage membrane separation process; the liquefaction unit is used for liquefying the captured carbon dioxide and comprises a compression assembly and a cooling assembly which are communicated in sequence; the curing unit is used for cooling and curing the liquid carbon dioxide; the storage tank is used for storing solid carbon dioxide.

Description

TECHNICAL FIELD

[0001] The utility model belongs to carbon dioxide gas capture technical field, concretely relates to a kind of carbon dioxide capture device based on membrane separation low-temperature condensation process. BACKGROUND

[0002] According to the different period of carbon and fuel separation, carbon dioxide capture path can be divided into several kinds such as pre-combustion capture, post-combustion capture and air capture;Capture technology mainly has chemical absorption method, physical adsorption method, membrane separation method and low-temperature condensation method etc.

[0003] Current CO2 capture technology research mostly concentrates on chemical absorption method and physical adsorption method, and low-temperature liquefaction separation CO2 is generally considered to be only applicable to the case of high CO2 concentration, using the different condensing points of CO2 and other components in mixed gas, gradually cooling mixed gas, different gas condenses and separates in turn, so as to obtain the technology of high-purity liquid carbon dioxide. At present, the low-temperature condensation technology of carbon dioxide in China is not perfect enough, and more mature normal-temperature liquefaction method is still used in many industrial occasions.

[0004] Although the existing carbon dioxide low-temperature condensation device structure is relatively simple, there are problems of low carbon dioxide purity and low carbon dioxide capture efficiency.

[0005] In view of this, the utility model thinks that it is necessary to improve the existing carbon dioxide low-temperature condensation technology. SUMMARY

[0006] The utility model discloses a kind of carbon dioxide capture device based on membrane separation low-temperature condensation process, to solve the low carbon dioxide purity and the low capture efficiency in the existing carbon dioxide low-temperature condensation technology, and provide a kind of carbon dioxide capture device based on membrane separation low-temperature condensation process.

[0007] To achieve the above object, the technical solution provided by the utility model is as follows:

[0008] A kind of carbon dioxide capture device based on membrane separation low-temperature condensation process, it is special in that, including pretreatment unit, membrane separation unit, liquefaction unit, solidification unit and storage tank;

[0009] The pretreatment unit is used to remove impurities in flue gas, and a flue gas inlet (external flue gas source) and a flue gas outlet are arranged thereon;Activated carbon can be used as adsorbent in the pretreatment unit;

[0010] The membrane separation unit is used to capture carbon dioxide in flue gas after pretreatment, and includes a primary membrane separation assembly, a secondary membrane separation assembly and a pressure gauge;The pressure gauge is used to observe the change of air pressure in the primary membrane separation assembly;Two-stage membrane separation process can effectively improve the concentration of captured carbon dioxide under controllable cost;

[0011] The liquefaction unit is used for liquefying the captured carbon dioxide, which comprises a compression assembly and a cooling assembly connected in sequence, i.e. the liquefaction unit is a compression-cooling integrated unit, the carbon dioxide is pressurized (1.6 MPa) by the compression assembly, and then the liquid carbon dioxide is formed by cooling (-30℃);

[0012] The solidification unit is used for solidifying the liquid carbon dioxide by cooling (-78.3℃);

[0013] The storage tank is used for storing the solid carbon dioxide;

[0014] The flue gas outlet of the pretreatment unit is communicated with the gas inlet of the primary membrane separation assembly, the carbon dioxide outlet of the primary membrane separation assembly is communicated with the gas inlet of the secondary membrane separation assembly, the residual gas outlet of the primary membrane separation assembly is communicated with the outside, the carbon dioxide outlet of the secondary membrane separation assembly is communicated with the inlet of the liquefaction unit, the residual gas outlet of the secondary membrane separation assembly is communicated with the gas inlet of the primary membrane separation assembly, the outlet of the liquefaction unit is communicated with the inlet of the solidification unit, and the outlet of the solidification unit is communicated with the storage tank.

[0015] Further, the residual gas outlet of the primary membrane separation assembly is also communicated with the gas inlet of the primary membrane separation assembly.

[0016] Further, the flue gas outlet of the pretreatment unit is communicated with the gas inlet of the primary membrane separation assembly through a first pipeline, and along the gas flow direction, a valve I and a gas pump I are arranged on the first pipeline;

[0017] The carbon dioxide outlet of the primary membrane separation assembly is communicated with the gas inlet of the secondary membrane separation assembly through a second pipeline, and along the gas flow direction, a valve II and a gas pump II are arranged on the second pipeline, which are used for pumping the enriched carbon dioxide of the primary membrane separation assembly into the secondary membrane separation assembly;

[0018] The residual gas outlet of the primary membrane separation assembly is communicated with the outside and the first pipeline through a composite pipeline; the composite pipeline comprises a main pipe, a first branch pipe and a second branch pipe; the first branch pipe is provided with a valve III (used for recycling the treated gas of the primary membrane separation assembly to the gas inlet of the gas pump I), and the second branch pipe is provided with a valve VIII (used for discharging the final residual gas after treatment); the residual gas of the primary membrane separation assembly is recycled to the gas inlet of the primary membrane separation assembly through the valve III, the valve I and the gas pump I; and the residual gas of the primary membrane separation assembly is discharged to the outside through the valve VIII;

[0019] The carbon dioxide outlet of the secondary membrane separation assembly is communicated with the inlet of the liquefaction unit through a carbon dioxide outlet pipe, and a valve V is arranged on the carbon dioxide outlet pipe; the excess gas outlet of the secondary membrane separation assembly is communicated to the first pipeline through a third pipeline, and a valve IV is arranged on the third pipeline; the excess gas of the secondary membrane separation assembly is returned to the gas inlet of the primary membrane separation assembly through the valve IV, the valve I and the gas pump I;

[0020] The outlet of the liquefaction unit is communicated with the inlet of the solidification unit through a fourth pipeline, and a valve VI is arranged on the fourth pipeline;

[0021] The outlet of the solidification unit is communicated with the storage tank through a fifth pipeline, and a valve VII is arranged on the fifth pipeline.

[0022] Further, the primary membrane separation assembly and the secondary membrane separation assembly are arranged in the same shell in an up-down arrangement and are isolated by a partition plate.

[0023] The primary membrane separation assembly and the secondary membrane separation assembly are both divided into two parts by a semi-permeable membrane, and the gas inlet and the excess gas outlet are both located below the semi-permeable membrane, and the carbon dioxide outlet is located above the semi-permeable membrane.

[0024] Further, a pressure gauge is arranged in the space below the semi-permeable membrane in the primary membrane separation assembly.

[0025] Further, the cooling assembly adopts a low-temperature refrigeration unit, the pipeline of which is arranged in an S shape, for achieving a controllable temperature and a cooling effect, and the pipeline is made of copper, which is economical and practical and can achieve the best refrigeration conduction effect.

[0026] Further, the compression assembly is a compressor.

[0027] Further, the gas pump I and the gas pump II are both axial flow type compression pumps, for increasing the flow rate of the gas flow so that the gas flow has the power to pass through the membrane separation device.

[0028] Further, the storage tank is made of stainless steel.

[0029] The utility model has the advantages that:

[0030] 1. The utility model discloses a carbon dioxide capture device and method, which can improve the carbon dioxide capture efficiency and the carbon dioxide purity.

[0031] 2. The utility model discloses a carbon dioxide capture device and method, which can realize the separation and purification of carbon dioxide through two-stage membrane separation assemblies in series connection, and realize the solidification and storage of carbon dioxide through a liquefaction unit and a solidification unit, so as to further utilize the CO2 resources.

[0032] 3. The utility model discloses a trapping device based on membrane separation principle design, simple structure, reliable ability, and through the air pump increases the power of membrane separation unit to improve carbon capture efficiency, the whole device is easy to manufacture, and the operating cost is lower. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is flow schematic drawing of the utility model trapping device;

[0034] The signs are as follows:

[0035] 1- flue gas inlet pipe, 2- pretreatment unit, 3- valve I, 4- air pump I, 5- membrane separation unit, 6- primary membrane separation subassembly, 7- valve III, 8- valve II, 9- air pump II, 10- secondary membrane separation subassembly, 11- valve IV, 12- carbon dioxide outlet pipe, 13- valve V, 14- liquefaction unit, 15- compression subassembly, 16- cooling subassembly, 17- valve VI, 18- solidification unit, 19- valve VII, 20- storage tank, 21- pressure gauge, 22- valve VIII. DETAILED DESCRIPTION

[0036] The contents of the utility model are further described in detail in combination with the drawings and specific embodiments:

[0037] Figure 1 As shown in the figure, a kind of carbon dioxide trapping device based on membrane separation low-temperature condensation process, its speciality is, including pretreatment unit, membrane separation unit, liquefaction unit, solidification unit and storage tank.

[0038] The pretreatment unit is used for removing impurities in flue gas, and a flue gas inlet and a flue gas outlet are arranged thereon; activated carbon can be used as an adsorbent in the pretreatment unit, and the flue gas inlet is connected with a flue gas source through a flue gas inlet pipe. The membrane separation unit is used for capturing carbon dioxide in the flue gas after pretreatment, and includes a primary membrane separation assembly and a secondary membrane separation assembly; wherein the primary membrane separation assembly and the secondary membrane separation assembly are arranged in an up-down manner in the same shell and are isolated by a partition plate; and the primary membrane separation assembly and the secondary membrane separation assembly are each divided into two by a semi-permeable membrane (a carbon dioxide permeable membrane with a good effect at present can be used), and the gas inlet and the remaining gas outlet are located below the semi-permeable membrane, and the carbon dioxide gas outlet is located above the semi-permeable membrane, wherein a pressure gauge is arranged in the space below the semi-permeable membrane in the primary membrane separation assembly. The liquefaction unit is used for liquefying the captured carbon dioxide, and includes a compression assembly and a cooling assembly which are sequentially connected, that is, the liquefaction unit is a compression-cooling integrated unit, the compression assembly (such as a compressor) is used to pressurize the carbon dioxide (1.6 MPa), and then the liquid carbon dioxide is formed by cooling (-30℃). The cooling assembly adopts a low-temperature refrigeration unit, the pipeline thereof is arranged in an S shape, and is used to achieve a controllable temperature to achieve a cooling effect, and the pipeline is made of aluminum to achieve the best refrigeration conduction effect. The solidification unit is used for solidifying the liquid carbon dioxide by cooling (-78.3℃), and adopts a low-temperature refrigeration unit to achieve a controllable temperature to achieve a solidification cooling effect. The storage tank is made of stainless steel and is used for storing solid carbon dioxide.

[0039] The flue gas outlet of the pretreatment unit is connected to the air inlet of the primary membrane separation assembly via a first pipeline. Valve I and air pump I are installed on the first pipeline along the gas flow direction. The carbon dioxide outlet of the primary membrane separation assembly is connected to the air inlet of the secondary membrane separation assembly via a second pipeline. Valve II and air pump II are installed on the second pipeline along the gas flow direction to pump the carbon dioxide enriched in the primary membrane separation assembly into the secondary membrane separation assembly. The residual gas outlet of the primary membrane separation assembly is connected to both the outside world and the first pipeline via a composite pipeline. The composite pipeline comprises a main pipeline, a first branch pipeline, and a second branch pipeline. Valve III is installed on the first branch pipeline, and valve VIII is installed on the second branch pipeline (to discharge the final residual gas after treatment). The residual gas from the primary membrane separation assembly flows back to the air inlet of the primary membrane separation assembly through valves III, valve I, and air pump I. The residual gas from the primary membrane separation assembly is then discharged to the outside world through valve VIII. The carbon dioxide outlet of the secondary membrane separation assembly is connected to the inlet of the liquefaction unit via a carbon dioxide outlet pipeline, which is equipped with valve V. The residual gas outlet of the secondary membrane separation assembly is connected to the first pipeline via a third pipeline, which is equipped with valve IV. The residual gas from the secondary membrane separation assembly flows back to the inlet of the primary membrane separation assembly through valve IV, valve I, and air pump I. The outlet of the liquefaction unit is connected to the inlet of the solidification unit via a fourth pipeline, which is equipped with valve VI. The outlet of the solidification unit is connected to the storage tank via a fifth pipeline, which is equipped with valve VII. Both air pumps I and II are axial flow compression pumps, used to increase the airflow velocity to enable it to pass through the membrane separation device.

[0040] The capture principle is:

[0041] During separation and purification, the flue gas passes through the pretreatment unit to remove micro-impurities and enters the first-level membrane separation component through air pump I. The first-level membrane separation component selectively permeates and enriches carbon dioxide, and then the enriched carbon dioxide is pumped to the second-level membrane separation component through air pump II for selective permeation of carbon dioxide again. Before solid-state storage, the enriched carbon dioxide is transported to the liquefaction unit for compression and cooling to liquid state (1.6MPa, -30℃, that is, increasing the pressure and lowering the temperature to reach the critical point of carbon dioxide liquefaction), and the remaining gas that is not selectively permeated is returned to the air inlet of the first-level membrane separation component for circulation. The liquid carbon dioxide passes through the solidification unit to reduce the system temperature again to reach the freezing point of carbon dioxide (-78.3℃), thereby achieving the purpose of solidifying and storing carbon dioxide and resource utilization of carbon dioxide.

[0042] The working process of the above device is as follows:

[0043] Open valve I 3, close valve II 8, valve III 7, flue gas through the flue gas inlet pipe 1 into the pretreatment unit 2, after activated carbon treatment of gas through the flue gas outlet; start gas pump I 4, gas by gas pump I 4 is pumped to the membrane separation unit 5, the first membrane separation assembly 6, the power generated makes the carbon dioxide in the flue gas selectively permeate the first membrane separation assembly semi-permeable membrane to the other side of the membrane to form an enrichment state, when the gas concentration on both sides of the membrane reaches equilibrium (whether in equilibrium state is observed by pressure gauge 21), open valve II 8, gas pump II 9, valve V 13, close gas pump I 4, valve I 3 and valve IV 11, after enrichment of carbon dioxide by gas pump II 9 is pumped to the second membrane separation assembly 10, and then through the second membrane separation assembly 10 semi-permeable membrane selectively permeates carbon dioxide to improve purity, the enriched carbon dioxide is directly sent to the liquefaction unit 14, when the carbon dioxide is significantly reduced and the pressure gauge 21 changes slowly (the pressure gauge 21 in the first membrane separation assembly changes from large to slow), close valve II 8, gas pump II 9, valve V 13, open valve III 7, valve IV 11, gas pump I 4, valve I 3, pump the gas that does not permeate the membrane separation unit back to the first membrane separation assembly to reduce the insufficient separation of carbon dioxide, and finally the gas that cannot permeate the membrane separation unit is discharged to the outside atmosphere by opening valve VIII 22; carbon dioxide gas entering the liquefaction unit 14 is compressed by compression assembly 15 to increase the pressure (1.6 MPa or more), and the temperature is reduced by S-shaped cooling assembly 16 pipeline to form liquid carbon dioxide (-30℃ or lower), open valve VI 17, liquid carbon dioxide enters the solidification unit 18 to further reduce the temperature (-78.3℃ or lower) to form solid carbon dioxide, open valve VII 19 to transport and store in the storage tank 20.

[0044] The above is a cycle process for completing carbon dioxide capture and storage, and repeating the above process can realize carbon dioxide capture from flue gas. The opening and closing of gas pump and valve, the start and stop of liquefaction unit and solidification unit in the whole working process can be automatically controlled by adding existing control unit.

Claims

1. A device for capturing carbon dioxide based on a membrane separation and low-temperature condensation process, characterized by: It includes a pretreatment unit, a membrane separation unit, a liquefaction unit, a solidification unit and a storage tank; The pretreatment unit is used to remove impurities in the flue gas, and is provided with a flue gas inlet and a flue gas outlet; The membrane separation unit is used to capture carbon dioxide in the pretreated flue gas, and includes a primary membrane separation component, a secondary membrane separation component, and a pressure gauge; the pressure gauge is used to observe the pressure change in the primary membrane separation component; The liquefaction unit is used to liquefy the captured carbon dioxide, and includes a compression component and a cooling component connected in sequence; The solidification unit is used to solidify liquid carbon dioxide; The storage tank is used to store solid carbon dioxide; The flue gas outlet of the pretreatment unit is connected to the air inlet of the first-level membrane separation component, the carbon dioxide outlet of the first-level membrane separation component is connected to the air inlet of the second-level membrane separation component, the residual gas outlet of the first-level membrane separation component is connected to the outside, the carbon dioxide outlet of the second-level membrane separation component is connected to the inlet of the liquefaction unit, the residual gas outlet of the second-level membrane separation component is connected to the air inlet of the first-level membrane separation component, the outlet of the liquefaction unit is connected to the inlet of the solidification unit, and the outlet of the solidification unit is connected to the storage tank.

2. The carbon dioxide capture device based on membrane separation and low-temperature condensation process according to claim 1 is characterized in that: The residual gas port of the first-stage membrane separation component is also communicated with the gas inlet of the first-stage membrane separation component.

3. The carbon dioxide capture device based on membrane separation and low-temperature condensation process according to claim 2, characterized in that: The flue gas outlet of the pretreatment unit is connected to the air inlet of the primary membrane separation assembly through a first pipe. Along the gas flow direction, a valve I and an air pump I are provided on the first pipe; The carbon dioxide outlet of the first membrane separation component is connected to the air inlet of the second membrane separation component through a second pipeline. A valve II and an air pump II are provided on the second pipeline along the direction of gas flow. The residual gas outlet of the first-stage membrane separation assembly is connected to the outside and the first pipeline at the same time through a composite pipeline; the composite pipeline includes a main pipeline, a first branch pipeline, and a second branch pipeline; a valve III is provided on the first branch pipeline, and a valve VIII is provided on the second branch pipeline; the residual gas of the first-stage membrane separation assembly is refluxed to the air inlet of the first-stage membrane separation assembly through valve III, valve I, and air pump I; and the residual gas of the first-stage membrane separation assembly is discharged to the outside through valve VIII; The carbon dioxide outlet of the secondary membrane separation assembly is connected to the inlet of the liquefaction unit through a carbon dioxide outlet pipe, and a valve V is provided on the carbon dioxide outlet pipe; the residual gas outlet of the secondary membrane separation assembly is connected to the first pipeline through a third pipeline, and a valve IV is provided on the third pipeline; the residual gas of the secondary membrane separation assembly is refluxed to the air inlet of the primary membrane separation assembly through valve IV, valve I and air pump I; The outlet of the liquefaction unit is connected to the inlet of the solidification unit through a fourth pipeline, and a valve VI is provided on the fourth pipeline; The outlet of the solidification unit is connected to the storage tank via a fifth pipeline, and a valve VII is provided on the fifth pipeline.

4. The carbon dioxide capture device based on membrane separation and low-temperature condensation process according to claim 3 is characterized in that: The first-stage membrane separation component and the second-stage membrane separation component are arranged in the same housing and separated by a partition. The first-stage membrane separation component and the second-stage membrane separation component both have their internal spaces divided into two by a semipermeable membrane, and the air inlet and the residual air outlet are both located below the semipermeable membrane, and the carbon dioxide outlet is located above the semipermeable membrane.

5. The carbon dioxide capture device based on membrane separation and low-temperature condensation process according to claim 4 is characterized in that: The cooling component adopts a low-temperature refrigeration unit, and its pipes are arranged in an S shape.

6. The carbon dioxide capture device based on membrane separation and low-temperature condensation process according to claim 5, characterized in that: The compression component is a compressor.

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