Carbon dioxide trapping system and method
By combining the membrane method and adsorption method, multi-stage membrane separation and adsorption treatment, combined with the energy recovery technology of the residual pressure recovery refrigeration device, the problems of low carbon dioxide capture rate and high energy consumption in the existing technology are solved, and high efficiency is achieved. Low energy consumption carbon dioxide capture effect.
Patent Information
- Application Number
- CN202310730044.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-19
- Publication Date
- 2024-12-20
AI Technical Summary
It is difficult to achieve comprehensive optimization of high capture rate and low energy consumption in carbon dioxide capture concentrations, especially for low concentration CO2 capture effect.
A system combining a membrane method and an adsorption method is adopted, including a first membrane separation device, a second membrane separation device, a first residual pressure recovery and refrigeration device and an adsorption device. Through multi-stage membrane separation and adsorption processing, refrigeration is recovered using residual pressure The device performs energy recovery, improves the capture rate of carbon dioxide and reduces energy consumption.
It achieves efficient carbon dioxide capture rate and low energy consumption, improves the purity of product gas, simplifies the operation process, reduces system energy consumption, and has a simple process, high efficiency and pollution-free process.
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Figure CN119158374A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the capture of carbon dioxide, and in particular to a carbon dioxide capture system and method capable of reducing energy consumption. Background Art
[0002] Solvent method, membrane method and adsorption method are the three most mainstream CO2 capture technologies. The solvent method mainly achieves CO2 capture by chemical absorption, with high capture rate and product purity, but high energy consumption and operating costs, and serious environmental pollution; the membrane method mainly achieves CO2 capture by physical separation, with low energy consumption, environmental friendliness, and flexible operation, but it is difficult to achieve a high product gas purity for the capture of low-concentration CO2; the adsorption method mainly achieves CO2 capture by physical adsorption, which also has the technical advantages of low energy consumption and environmental friendliness, but for the capture of low-concentration CO2, a multi-stage adsorption process is required, which occupies a large area, is complex to operate, and has low efficiency.
[0003] However, the methods for capturing carbon dioxide by coupling the membrane method with the adsorption method disclosed in the prior art either have a low CO2 capture rate or high energy consumption, and cannot achieve the comprehensive optimization of high capture rate and low energy consumption. Summary of the invention
[0004] In order to overcome at least one defect of the above-mentioned prior art, in the first aspect, an embodiment of the present invention provides a carbon dioxide capture system, including a first membrane separation device, a second membrane separation device, a first residual pressure recovery refrigeration device and an adsorption device; wherein the first membrane separation device is used to perform membrane separation treatment on the flue gas to be treated to obtain a first permeate gas and a first retentate gas; the second membrane separation device is used to perform membrane separation treatment on the first retentate gas to obtain a second permeate gas and a second retentate gas; the first residual pressure recovery refrigeration device is used to pressurize the first permeate gas by expanding the second retentate gas; and the adsorption device is used to adsorb carbon dioxide on the pressurized first permeate gas.
[0005] In a second aspect, an embodiment of the present invention provides a method for capturing carbon dioxide, comprising the following steps:
[0006] The flue gas to be treated is subjected to a first membrane separation treatment to obtain a first permeate gas and a first retentate gas;
[0007] subjecting the first retentate gas to a second membrane separation process to obtain a second permeate gas and a second retentate gas;
[0008] Pressurizing the first permeate gas by expanding the second retentate gas to do work; and
[0009] The pressurized first permeate gas is subjected to a process of adsorbing carbon dioxide by using an adsorbent.
[0010] A carbon dioxide capture system / method according to one embodiment of the present invention can improve the capture rate of carbon dioxide and reduce energy consumption by combining the technical advantages of a membrane method and an adsorption method. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The accompanying drawings are only used to illustrate specific embodiments and are not to be considered as limiting the present invention.
[0012] Figure 1 A schematic structural diagram of a carbon dioxide capture system according to an embodiment of the present invention;
[0013] Figure 2 A schematic diagram of the structure of a carbon dioxide capture system of a comparative example;
[0014] The following are the descriptions of the reference numerals:
[0015] 10. Boiler; 11. Pretreatment device; 12. Booster; 13. Heat exchanger; 14. Gas-liquid separator; 20. First membrane separation device; 30. Second membrane separation device; 31. Air blower; 41. First adsorption tower; 42. Second adsorption tower; 43. Third adsorption tower; 44. Pump; 51. First residual pressure recovery refrigeration device; 52. Second residual pressure recovery refrigeration device; 61. Second residual gas pipeline; 62. Exhaust pipeline; 63. First permeate gas pipeline; 64. Desorption pipeline;
[0016] 1. Pretreatment device; 2. Booster; 3. Heat exchanger; 4. Gas-liquid separator; 5. First membrane separation device; 6. Second membrane separation device; 7. Adsorption device. DETAILED DESCRIPTION
[0017] Typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various variations in different embodiments without departing from the scope of the present invention, and the descriptions therein are essentially for the purpose of illustration rather than for limiting the present invention. According to the description of the process flow, the part "connected" herein includes the meaning of being connected.
[0018] Reference Figure 1As shown, an embodiment of the present invention provides a carbon dioxide capture system, including a first membrane separation device 20, a second membrane separation device 30, a first residual pressure recovery refrigeration device 51 and an adsorption device; wherein the first membrane separation device 20 is used to perform membrane separation treatment on the flue gas to be treated to obtain a first permeate gas and a first retentate gas; the second membrane separation device 30 is used to perform membrane separation treatment on the first retentate gas for carbon dioxide to obtain a second permeate gas and a second retentate gas; the first residual pressure recovery refrigeration device 51 is used to pressurize the first permeate gas by expanding the second retentate gas; the adsorption device is connected to the first residual pressure recovery refrigeration device 51, and is used to adsorb carbon dioxide on the pressurized first permeate gas.
[0019] In one embodiment, the flue gas to be treated may be flue gas containing carbon dioxide, such as flue gas generated by combustion of pulverized coal in the boiler 10 .
[0020] In one embodiment, the carbon dioxide capture system includes a pretreatment component, and the flue gas to be treated can be pretreated by the pretreatment component first, and then subjected to membrane separation treatment. Further, the pretreatment component includes a pretreatment device 11, a booster 12, a heat exchanger 13 and a gas-liquid separator 14 connected in sequence; wherein the pretreatment device 11 is used to perform desulfurization and dust removal treatment on the flue gas to be treated, and the pretreatment device 11 can be, for example, an alkali liquid water washing tower / water washing tower; the booster 12 is used to pressurize the flue gas after desulfurization and dust removal treatment, the heat exchanger 13 is used to perform heat exchange treatment on the pressurized flue gas, and the gas-liquid separator 14 is used to perform gas-liquid separation treatment on the flue gas after heat exchange, and through pressurization, heat exchange, gas-liquid separation and other treatments, the flue gas can reach the temperature and pressure required for subsequent membrane separation treatment.
[0021] In one embodiment, the gas-liquid separator 14 includes a gas outlet and a liquid outlet. The flue gas after heat exchange is treated by the gas-liquid separator 14 to form deliquidized flue gas and condensed water. The deliquidized flue gas is discharged from the gas-liquid separator 14 from the gas outlet and enters the first membrane separation device 20 for membrane separation treatment, and the condensed water is discharged from the gas-liquid separator 14 from the liquid outlet.
[0022] In one embodiment, the first membrane separation device 20 and the second membrane separation device 30 may both be existing devices used for membrane separation processing to separate carbon dioxide, such as an existing carbon dioxide membrane separator.
[0023] In one embodiment, the first membrane separation device 20 includes a first air inlet, a first air outlet and a second air outlet, wherein the first air inlet is connected to the air outlet of the gas-liquid separator 14, the first air outlet is connected to the second membrane separation device 30, and the second air outlet is connected to the adsorption device.
[0024] In one embodiment, the first retentate gas is subjected to membrane separation treatment of carbon dioxide by the second membrane separation device 30, which can further reduce the concentration of carbon dioxide in the exhaust flue gas and improve the capture rate of carbon dioxide.
[0025] In one embodiment, a second retentate gas pipeline 61 is provided between the second membrane separation device 30 and the adsorption device, and the first residual pressure recovery refrigeration device 51 is connected to the second retentate gas pipeline 61. The low-temperature second retentate gas after expansion and work can enter the adsorption device through the second retentate gas pipeline 61 and contact with the adsorbent therein to cool the adsorbent. While the adsorbent is cooling, it will adsorb the low-temperature second retentate gas, further improving the capture rate of carbon dioxide, and the gas not adsorbed by the adsorbent is discharged from the adsorption device as exhaust gas. In addition, cooling the adsorbent can improve its ability to adsorb carbon dioxide, which is beneficial to the adsorption of carbon dioxide in the first permeate gas, and can further improve the capture rate of carbon dioxide.
[0026] In one embodiment, the second membrane separation device 30 is also connected to the boiler 10. Under the action of the air blower 31, air can be introduced into the permeation side of the second membrane separation device 30 for purging. The air purging method can increase the concentration difference of carbon dioxide on both sides of the inner membrane of the second membrane separation device 30, improve the separation effect, and further improve the carbon dioxide capture rate of the system; the purged air can be directly returned to the boiler 10 for secondary utilization to increase the carbon dioxide concentration in the feed gas, further improve the carbon dioxide capture rate of the system, and reduce the energy consumption of the system.
[0027] In one embodiment, an exhaust pipe 62 connected to the adsorption device is provided outside the adsorption device, and the exhaust gas discharged from the adsorption device can be discharged outside the system through the exhaust pipe 62; further, the exhaust gas can be discharged outside the system after energy recovery. A second residual pressure recovery refrigeration device 52 is provided on the exhaust pipe 62, and the second residual pressure recovery refrigeration device 52 can be used to recover the pressure energy of the exhaust gas.
[0028] In one embodiment, a first permeate gas pipeline 63 is provided between the first membrane separation device 20 and the adsorption device, and the first permeate gas can enter the adsorption device through the first permeate gas pipeline 63. The first residual pressure recovery refrigeration device 51 can be connected to the second permeate gas pipeline 61 and the first permeate gas pipeline 63, respectively, so as to increase the pressure of the first permeate gas by expanding the second permeate gas.
[0029] In one embodiment, the second excess pressure recovery refrigeration device 52 is connected to the exhaust pipeline 62 and the first permeate gas pipeline 63 respectively, and the exhaust gas can expand through the second excess pressure recovery refrigeration device 52 to do work and increase the pressure of the first permeate gas.
[0030] In one embodiment, on the first permeate gas pipeline 63, the first residual pressure recovery refrigeration device 51 is arranged between the first membrane separation device 20 and the second residual pressure recovery refrigeration device 52, and the second residual pressure recovery refrigeration device 52 is arranged between the first residual pressure recovery refrigeration device 51 and the adsorption device.
[0031] In one embodiment, the first waste pressure recovery refrigeration device 51 and the second waste pressure recovery refrigeration device 52 can be existing devices for achieving pressurization and / or cooling based on gas expansion work, which can be, for example, a combined expander-compressor system, that is, the compressor is driven to work by the gas entering the turboexpander.
[0032] In one embodiment, an adsorbent is provided in the adsorption device, and the adsorbent is used to adsorb carbon dioxide on the pressurized first permeate gas (low-purity carbon dioxide crude stripping gas), so that carbon dioxide can be re-concentrated. Furthermore, the adsorbent provided in the adsorption device can be an existing adsorbent, preferably an adsorbent with better adsorption performance at low temperatures (e.g., -20°C to 10°C), such as activated carbon, molecular sieves, or adsorbents prepared from coal liquefaction asphalt residues. The selection of the above adsorbent enables the adsorption performance of the adsorbent to be further improved by cooling the second permeate gas.
[0033] In one embodiment, a pump 44 connected to the adsorption device is provided outside the adsorption device for removing carbon dioxide from the adsorbent adsorbed with carbon dioxide in the adsorption device. The carbon dioxide gas adsorbed by the adsorbent can be vacuum regenerated by the pump 44 to obtain a high-purity CO2 product gas; wherein the pump 44 can be a vacuum pump. Further, the pump 44 is connected to the adsorption device through a desorption pipeline 64.
[0034] In one embodiment, the adsorption device may include one or more adsorption towers. The number of adsorption towers may be, for example, 3 to 12. Multiple adsorption towers may be arranged in parallel. For example, the adsorption device includes three adsorption towers arranged in parallel, namely, a first adsorption tower 41, a second adsorption tower 42, and a third adsorption tower 43. The first adsorption tower 41, the second adsorption tower 42, and the third adsorption tower 43 have the same structure and may be existing devices.
[0035] In one embodiment, the first adsorption tower 41 includes a feed port and a discharge port, the discharge port is connected to the exhaust pipeline 62, the feed port is respectively connected to the second retentate gas pipeline 61, the first permeate gas pipeline 63, and the desorption pipeline 64, and the three pipelines can be individually connected to the first adsorption tower 41 by the control of a control component (such as a control valve) to perform cooling, adsorption, and desorption of the adsorbent in the first adsorption tower 41. The connection relationship between the second adsorption tower 42 and the third adsorption tower 43 and the exhaust pipeline 62, the second retentate gas pipeline 61, the first permeate gas pipeline 63, and the desorption pipeline 64 is the same as that of the first adsorption tower 41. When operating, the cooling, adsorption, and desorption processes of the adsorbent can be performed in the three adsorption towers to achieve continuous carbon dioxide capture.
[0036] In one embodiment, the heat exchanger 13 is connected to the exhaust pipeline 62, and is used to perform heat exchange treatment on the exhaust gas after expansion and work with the flue gas to be treated, so as to cool the flue gas to be treated and obtain exhaust gas, which is discharged from the system. By performing two treatments of the exhaust gas, such as expansion and heat exchange, the full recovery and utilization of energy is achieved.
[0037] One embodiment of the present invention provides a method for capturing carbon dioxide, which can be implemented using the above system. The method comprises the following steps:
[0038] The flue gas to be treated is subjected to a first membrane separation treatment to obtain a first permeate gas and a first retentate gas;
[0039] subjecting the first retentate gas to a second membrane separation process to obtain a second permeate gas and a second retentate gas;
[0040] Pressurizing the first permeate gas by expanding the second retentate gas; and
[0041] The pressurized first permeate gas is treated by adsorbing carbon dioxide through an adsorbent.
[0042] In one embodiment, the flue gas to be treated may be pretreated, and the pretreatment includes desulfurization and dust removal, pressurization, heat exchange and gas-liquid separation. The flue gas to be treated may be pretreated by the above-mentioned pretreatment components.
[0043] In one embodiment, the flue gas may be subjected to membrane separation treatment of carbon dioxide by the first membrane separation device 20, and further, the first retentate gas may be subjected to membrane separation treatment of carbon dioxide by the second membrane separation device 30. The inlet pressure of the first membrane separation device 20 and the second membrane separation device 30 may be 0.1-1 MPa (A), such as 0.2 MPa, 0.3 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa; the inlet temperature may be 10-50°C, such as 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C.
[0044] In one embodiment, the concentration of carbon dioxide in the first permeate gas may be no less than 40%.
[0045] In one embodiment, the pressurized first permeate gas can be treated by adsorbing carbon dioxide through an adsorption device (such as an adsorption tower), wherein the adsorption pressure of the adsorption tower can be 0.1-1 MPa (A), for example, 0.2 MPa, 0.3 MPa, 0.5 MPa, 0.8 MPa; the temperature of the adsorption tower can be -20-10°C, for example, -15°C, -10°C, -5°C, 0°C, 5°C.
[0046] In one embodiment, the second permeate side of the second membrane separation process may be purged with air.
[0047] In one embodiment, the adsorbent can be cooled by the low-temperature second retentate gas after expansion to obtain exhaust gas; while cooling the adsorbent, it can also adsorb the carbon dioxide contained in the second retentate gas, further improving the capture rate of carbon dioxide and reducing the content of carbon dioxide in the exhaust gas.
[0048] In one embodiment, the adsorbent can perform low-temperature adsorption of the first permeate gas by cooling the adsorbent with the low-temperature second permeate gas. The temperature of the low-temperature adsorption can be -20 to 10°C, such as -15°C, -10°C, -5°C, 0°C, or 5°C.
[0049] In one embodiment, the adsorbent adsorbed with carbon dioxide can be treated to remove carbon dioxide to obtain carbon dioxide product gas, for example, desorption can be performed by low pressure, and the desorption pressure of the adsorption tower can be 0-0.1MPa(A), for example, 0.01MPa, 0.02MPa, 0.05MPa, 0.08MPa.
[0050] In one embodiment, the first permeate gas or the pressurized first permeate gas may be further pressurized by performing work by expanding the exhaust gas.
[0051] In one embodiment, the exhaust gas after expansion and work is performed can be subjected to heat exchange treatment with the flue gas to be treated.
[0052] In one embodiment, the energy recovery of the expansion work can be achieved by the first excess pressure recovery refrigeration device 51 and the second excess pressure recovery refrigeration device 52, and the energy recovery rate is not less than 30%, for example, 50%.
[0053] A carbon dioxide capture system / method according to one embodiment of the present invention can achieve efficient capture of carbon dioxide with high capture rate, high product gas purity and low energy consumption by combining the technical advantages of membrane method and adsorption method.
[0054] A carbon dioxide capture method according to one embodiment of the present invention has simple process, high efficiency, flexible operation, no pollution and low energy consumption.
[0055] A carbon dioxide capture system / method according to one embodiment of the present invention can further reduce the capture energy consumption of the system by effectively recovering and utilizing the energy and heat of the system through a residual pressure recovery refrigeration device.
[0056] In one embodiment of the present invention, a carbon dioxide capture system / method recovers the energy of the second permeate gas discharged from the second membrane separation device 30 through a first residual pressure recovery refrigeration device 51, and uses the energy to pressurize the first permeate gas (low-purity CO2 crude stripping gas) discharged from the first membrane separation device 20 to achieve efficient energy utilization and further reduce system energy consumption; the obtained low-temperature second permeate gas is passed into an adsorption tower to cool the adsorbent while re-adsorbing carbon dioxide, which can further increase the carbon dioxide capture rate of the system and obtain an exhaust gas with an ultra-low carbon dioxide concentration; the exhaust gas is recovered through a second residual pressure recovery refrigeration device 52 and a heat exchanger 13 to recover energy and heat, thereby achieving efficient energy and heat utilization and further reducing energy consumption.
[0057] Hereinafter, the use of a carbon dioxide capture system according to an embodiment of the present invention will be further described in conjunction with the accompanying drawings and specific examples.
[0058] Example 1
[0059] S1: The flue gas generated by the combustion of pulverized coal in the boiler 10 is subjected to denitration, dust removal and desulfurization treatment. The temperature of the flue gas after treatment is 50-70°C and the pressure is slightly higher than the atmospheric pressure; then the flue gas is pressurized to 0.6MPa(A) by the booster 12, and the flue gas is cooled to 40°C by the heat exchanger 13. The flue gas is further dehydrated by the gas-liquid separator 14 and then passed into the first membrane separation device 20 for carbon dioxide separation through electric heating and constant temperature insulation to obtain a first permeate gas (carbon dioxide crude stripping gas) rich in carbon dioxide and a first retentate gas; wherein the concentration of carbon dioxide in the flue gas inlet of the first membrane separation device 20 is about 15vol%;
[0060] S2: The high-pressure first retentate gas is directly introduced into the second membrane separation device 30 through electric heating and temperature preservation for secondary carbon dioxide separation. The inlet pressure of the second membrane separation device 30 is 0.59 MPa (A) and the inlet temperature is 40°C. The second permeate gas and the second retentate gas are obtained through separation treatment by the second membrane separation device 30. During the separation process, air is introduced into the permeate side of the second membrane separation device 30 for purging, and the purged air is directly returned to the boiler 10 for secondary utilization.
[0061] S3: passing the second filtrate gas into the second filtrate gas pipeline 61, and recovering energy through the first residual pressure recovery refrigeration device 51 on the second filtrate gas pipeline 61, with an energy recovery rate of 50%, to obtain a low-temperature second filtrate gas after cooling; passing the low-temperature second filtrate gas into the adsorption tower for heat exchange with the adsorbent, cooling the adsorbent to about 5°C, and obtaining exhaust gas; the exhaust gas is discharged from the adsorption tower and pressurized for the first permeate gas through the second residual pressure recovery refrigeration device 52 arranged on the exhaust pipeline 62, and further cooling the flue gas to be treated through the heat exchanger 13, and then discharged from the system; the CO2 concentration of the exhaust gas discharged from the system is about 0.6vol%;
[0062] S4: The first permeate gas rich in carbon dioxide (CO2 concentration is about 58 vol%) is introduced into the first permeate gas pipeline 63, and is pressurized to 0.28 MPa (A) by the first excess pressure recovery refrigeration device 51 and the second excess pressure recovery refrigeration device 52. The pressurized first permeate gas enters the adsorption tower, and the adsorbent in the adsorption tower adsorbs carbon dioxide on the first permeate gas;
[0063] S5: After the adsorption treatment of step S4 is completed, low pressure conditions are provided to the adsorption tower through pump 44 to desorb carbon dioxide (the desorption pressure is about 0.01 MPa (A)), so that the carbon dioxide captured by the adsorbent is regenerated through vacuum, and finally a CO2 product gas with a purity of 99% is obtained.
[0064] Among them, after calculation, the carbon dioxide capture rate of the entire system is about 97%, and the carbon dioxide capture energy consumption is about 1.9GJ / tCO2.
[0065] Example 2
[0066] S1: The flue gas generated by the combustion of pulverized coal in the boiler 10 is subjected to denitration, dust removal and desulfurization treatment, and the temperature of the flue gas after treatment is 50-70°C and the pressure is slightly higher than the atmospheric pressure; then the flue gas is pressurized to 0.7MPa(A) by a booster, and the flue gas is cooled to 30°C by a heat exchanger 13, and the flue gas is further dehydrated by a gas-liquid separator 14, and then the flue gas is passed into the first membrane separation device 20 for carbon dioxide separation through electric heating and constant temperature insulation to obtain a first permeate gas and a first retentate gas rich in carbon dioxide; wherein the concentration of carbon dioxide in the flue gas inlet of the first membrane separation device 20 is about 13vol%;
[0067] S2: The high-pressure first retentate gas is directly introduced into the second membrane separation device 30 through electric heating and temperature preservation for secondary carbon dioxide separation. The inlet pressure of the second membrane separation device 30 is 0.68 MPa (A) and the inlet temperature is 30°C. After being processed by the second membrane separation device 30, a second permeate gas and a second retentate gas are obtained. Air is introduced into the permeate side of the second membrane separation device 30 for purging, and the purged air is directly returned to the boiler 10 for secondary utilization.
[0068] S3: passing the second filtrate gas into the second filtrate gas pipeline 61, and recovering energy through the first residual pressure recovery refrigeration device 51 on the second filtrate gas pipeline 61, with an energy recovery rate of 50%, to obtain a low-temperature second filtrate gas after cooling; passing the low-temperature second filtrate gas into the adsorption tower for heat exchange with the adsorbent, cooling the adsorbent to about 0°C, and obtaining exhaust gas; the exhaust gas is discharged from the adsorption tower and pressurized for the first permeate gas through the second residual pressure recovery refrigeration device 52 arranged on the exhaust pipeline 62, and further cooling the flue gas to be treated through the heat exchanger 13, and then discharged from the system; the CO2 concentration of the exhaust gas discharged from the system is about 0.4 vol%;
[0069] S4: The first permeate gas rich in carbon dioxide (CO2 concentration is about 53 vol%) is introduced into the first permeate gas pipeline 63, and is pressurized to 0.3 MPa (A) by the first excess pressure recovery refrigeration device 51 and the second excess pressure recovery refrigeration device 52. The pressurized first permeate gas enters the adsorption tower, and the adsorbent in the adsorption tower adsorbs carbon dioxide on the first permeate gas;
[0070] S5: After the adsorption treatment of step S4 is completed, low pressure conditions are provided to the adsorption tower through pump 44 to desorb carbon dioxide (the desorption pressure is about 0.02 MPa (A)), so that the carbon dioxide captured by the adsorbent is regenerated through vacuum, and finally a CO2 product gas with a purity of 96% is obtained.
[0071] Among them, after calculation, the carbon dioxide capture rate of the entire system is about 97%, and the carbon dioxide capture energy consumption is about 2.1GJ / tCO2.
[0072] Comparative Example
[0073] Reference Figure 2 As shown, this example uses the same raw material as that of Example 1 as the gas to be treated, and the process conditions involved are the same as those of Example 1; the specific process is: first, the flue gas is subjected to denitration, dust removal, and desulfurization treatment through a pretreatment device 1, and then pressurized, heat exchanged, and dehydrated through a booster 2, a heat exchanger 3, and a gas-liquid separator 4 in sequence;
[0074] Afterwards, the flue gas discharged from the gas-liquid separator 4 is subjected to membrane separation treatment through the first membrane separation device 5 to obtain permeate gas I and retentate gas I. The retentate gas I is further subjected to membrane separation treatment through the second membrane separation device 6 to obtain permeate gas II and retentate gas II. The permeate gas II is returned to the feed pipeline of the booster 2 for recycling and reuse, and the retentate gas II is directly discharged from the system as exhaust gas.
[0075] The permeated gas I is passed into the adsorption device 7, and the carbon dioxide in the permeated gas I is adsorbed by the adsorbent therein, and the unadsorbed gas is directly discharged from the system as exhaust gas; low-pressure conditions are provided to the adsorption device 7 by a pump to desorb carbon dioxide, so that the carbon dioxide captured by the adsorbent is regenerated through vacuum to obtain CO2 product gas.
[0076] Among them, after calculation, the carbon dioxide capture rate of the entire system is about 85%, and the carbon dioxide capture energy consumption is about 4.0GJ / tCO2.
[0077] Comparing Example 1 of the present invention with the comparative example, it can be seen that the structures of the carbon dioxide capture systems used in the two are relatively similar, and the main difference is that Example 1 further recycles the energy of the materials in the process flow. By comparing the results, it can be seen that the carbon dioxide capture rate of 97% in Example 1 is significantly higher than the carbon dioxide capture rate of 85% in the comparative example, and the capture energy consumption of 1.9 GJ / tCO2 in Example 1 is much lower than the capture energy consumption of 4.0 GJ / tCO2 in the comparative example. Therefore, the embodiment of the present invention makes full use of the energy of the second residual gas and the exhaust gas through the arrangement of the first residual pressure recovery refrigeration device 51, the second residual pressure recovery refrigeration device 52, the second residual gas pipeline 61, etc., thereby improving the capture rate of carbon dioxide and reducing the capture energy consumption.
[0078] Unless otherwise defined, the terms used in the present invention have the meanings commonly understood by those skilled in the art.
[0079] The embodiments described in the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Those skilled in the art may make various other substitutions, changes and improvements within the scope of the present invention. Therefore, the present invention is not limited to the above embodiments, but is only limited by the claims.
Claims
1. A carbon dioxide capture system comprising: A first membrane separation device, used for performing membrane separation treatment on the flue gas to be treated to obtain a first permeate gas and a first retentate gas; a second membrane separation device, used for performing membrane separation treatment on the first retentate gas to obtain a second permeate gas and a second retentate gas; a first residual pressure recovery refrigeration device, used for increasing the pressure of the first permeate gas by expanding the second permeate gas to do work; as well as The adsorption device is used for adsorbing carbon dioxide on the pressurized first permeate gas.
2. The system according to claim 1, wherein: A second retentate gas pipeline is provided between the second membrane separation device and the adsorption device, the first residual pressure recovery refrigeration device is connected to the second retentate gas pipeline, and the second retentate gas after expansion and work can enter the adsorption device through the second retentate gas pipeline to cool the adsorbent therein to obtain exhaust gas; and / or, A pump connected to the adsorption device is arranged outside the adsorption device for removing carbon dioxide from the adsorbent adsorbed with carbon dioxide in the adsorption device.
3. The system according to claim 2, wherein: An exhaust pipeline connected to the adsorption device is arranged outside the adsorption device, and a second residual pressure recovery refrigeration device is arranged on the exhaust pipeline; and / or, A first permeate gas pipeline is arranged between the first membrane separation device and the adsorption device, and the first residual pressure recovery refrigeration device is connected to the first permeate gas pipeline.
4. The system according to claim 3, wherein: The second excess pressure recovery refrigeration device is connected to the first permeate gas pipeline, and the exhaust gas can expand through the second excess pressure recovery refrigeration device to perform work to increase the pressure of the first permeate gas.
5. The system according to claim 4, wherein: A heat exchanger is arranged on the exhaust pipeline for performing heat exchange between the exhaust gas after expansion and the flue gas to be treated.
6. The system according to claim 5 comprises a pretreatment component for pretreating the flue gas to be treated; the pretreatment component comprises a pretreatment device, a booster, the heat exchanger and a gas-liquid separator connected in sequence, and the pretreatment device is used to desulfurize and remove dust from the flue gas to be treated.
7. A method for capturing carbon dioxide, comprising the following steps: The flue gas to be treated is subjected to a first membrane separation treatment to obtain a first permeate gas and a first retentate gas; subjecting the first retentate gas to a second membrane separation process to obtain a second permeate gas and a second retentate gas; Pressurizing the first permeate gas by expanding the second retentate gas to do work; as well as The pressurized first permeate gas is subjected to a process of adsorbing carbon dioxide by using an adsorbent.
8. The method according to claim 7, wherein: The adsorbent is cooled by the second retentate gas after expansion to obtain exhaust gas; and / or, removing carbon dioxide from the adsorbent adsorbed with carbon dioxide; and / or, The second permeate side of the second membrane separation process is purged with air.
9. The method according to claim 8, wherein: Performing pressurization processing on the first permeate gas or the pressurized first permeate gas by expanding the exhaust gas to do work; and / or, The second retentate gas after expansion is brought into contact with the adsorbent to be cooled, and the first permeate gas after pressurization is adsorbed with carbon dioxide by the adsorbent after the cooling.
10. The method according to claim 9, wherein: Performing heat exchange treatment on the exhaust gas after expansion and the flue gas to be treated; and / or, The method comprises pre-treating the flue gas to be treated, wherein the pre-treatment comprises desulfurization and dust removal treatment, pressurization treatment, heat exchange treatment and gas-liquid separation treatment.