Tubular parallel-flow carbon dioxide absorption and desorption continuous operation system and method

Abstract

The present invention belongs to the technical field of carbon dioxide capture, and specifically discloses a tubular parallel-current carbon dioxide absorption and desorption continuous operation system and method. It is used to solve the problems of large equipment volume, high operating cost and high energy consumption of the traditional countercurrent packed tower chemical absorption method. The operating system includes a low partial pressure carbon dioxide inlet, a carbon dioxide ejector, an absorption reactor, a first gas-liquid separator, a first heat exchanger, a second heat exchanger, a rich liquid pump, a desorption reactor, a heater, a pressure controller, a second gas-liquid separator, a third gas-liquid separator, an absorbent storage tank and a lean liquid pump. The present invention adopts continuous operation throughout the whole process, realizes the efficient recycling of carbon dioxide absorbent, effectively reduces the number of carbon capture equipment and the floor space, reduces labor costs and operation risks, improves carbon capture efficiency, and reduces the cost of transformation and maintenance of existing equipment, so as to realize parallel-current continuous operation of efficient, low-energy consumption green carbon dioxide absorption and desorption.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide capture, and in particular relates to a tubular parallel-flow carbon dioxide absorption and desorption continuous operation system and method. Background Art

[0002] Carbon capture is currently an important technical means to achieve large-scale greenhouse gas emission reduction, and it is also the only technical option to achieve low-carbon utilization of fossil energy. So far, a variety of carbon dioxide capture technologies such as physical adsorption or chemical absorption, membrane separation or molecular sieve, amine physical adsorption, amine washing, etc. have been put into practice on a laboratory scale or in industry. However, the above technologies have exposed many problems in the actual application process, such as insufficient carbon dioxide capture capacity, easy corrosion of equipment, and high energy consumption in the absorbent regeneration process, which seriously restricts the improvement of the economic benefits of enterprises.

[0003] Carbon capture is mainly divided into the absorption process and desorption process of carbon dioxide. At present, industrial carbon capture equipment is still mainly based on traditional packed towers and adopts countercurrent chemical absorption. However, the traditional countercurrent packed tower chemical absorption method has problems such as large equipment size, high operating cost, and high energy consumption. Therefore, it is urgent to introduce a new carbon capture method to achieve efficient, economical and environmentally friendly carbon capture. Summary of the invention

[0004] The purpose of the present invention is to provide a tubular parallel-current carbon dioxide absorption and desorption continuous operation system, which effectively solves the problems of large equipment volume, high operating cost and high energy consumption of the traditional countercurrent packed tower chemical absorption method.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a tubular parallel-current carbon dioxide absorption and desorption continuous operation system, including a low partial pressure carbon dioxide inlet, a carbon dioxide ejector, an absorption reactor, a first gas-liquid separator, a first heat exchanger, a second heat exchanger, a rich liquid pump, a desorption reactor, a heater, a pressure controller, a second gas-liquid separator, a third gas-liquid separator, an absorbent storage tank and a lean liquid pump.

[0006] The low partial pressure carbon dioxide inlet is connected to the gas phase inlet of the carbon dioxide ejector, the outlet of the carbon dioxide ejector is connected to the inlet of the absorption reactor, the outlet of the absorption reactor is connected to the inlet of the first gas-liquid separator, the liquid phase outlet of the first gas-liquid separator is connected to the first inlet of the first heat exchanger, the first outlet of the first heat exchanger is connected to the first inlet of the second heat exchanger, the first outlet of the second heat exchanger is connected to the inlet of the rich liquid pump, and the outlet of the rich liquid pump is connected to the inlet of the desorption reactor.

[0007] The heater is used to provide thermal energy for the desorption reactor, the pressure controller is connected to the series pipeline of the desorption reactor, the outlet of the pressure controller is connected to the inlet of the second gas-liquid separator, the liquid phase outlet of the second gas-liquid separator is connected to the inlet of the rich liquid pump, the outlet of the desorption reactor is connected to the inlet of the third gas-liquid separator, the gas phase outlet of the third gas-liquid separator is connected to the second inlet of the first heat exchanger, the liquid phase outlet of the third gas-liquid separator is connected to the second inlet of the second heat exchanger, the second outlet of the second heat exchanger is connected to the inlet of the absorbent storage tank, the outlet of the absorbent storage tank is connected to the inlet of the lean liquid pump, and the outlet of the lean liquid pump is connected to the liquid phase inlet of the carbon dioxide ejector.

[0008] Furthermore, the carbon dioxide ejector is used to inject point source low partial pressure carbon dioxide gas into the pipeline for parallel absorption and desorption; the absorption reactor is used to absorb carbon dioxide from point source low partial pressure carbon dioxide gas from related industries including thermal power plants, coal power plants, and downstream petrochemical industries, and transport the absorbed gas-liquid mixture to the first gas-liquid separator.

[0009] The first gas-liquid separator is used to separate the gas-liquid mixture after absorption in the absorption reactor into purified gas and rich liquid; the first heat exchanger uses the high-temperature second regenerated gas after desorption to perform a first preheating of the low-temperature rich liquid separated by the first gas-liquid separator, thereby realizing the reuse of waste heat of the high-temperature second regenerated gas; the second heat exchanger uses the high-temperature lean liquid after desorption to perform a second preheating of the rich liquid preheated by the first heat exchanger, thereby realizing the reuse of waste heat of the high-temperature lean liquid; the rich liquid pump is used to pump the rich liquid after the second preheating into the desorption reactor.

[0010] The desorption reactor is used to desorb the carbon dioxide in the tube by heating and raising the temperature, and the desorbed gas-liquid mixture is transported to the third gas-liquid separator; the pressure controller is used to control the pressure in the desorption reactor, and when a large amount of carbon dioxide is desorbed and the pressure exceeds a predetermined value, part of the gas-liquid mixture in the tube is transported to the second gas-liquid separator; the second gas-liquid separator is used to separate the gas-liquid mixture transported by the pressure controller into a first regenerated gas and an incompletely desorbed liquid, and the incompletely desorbed liquid is pumped into the desorption reactor again by a rich liquid pump.

[0011] The third gas-liquid separator is used to separate the gas-liquid mixture after desorption in the desorption reactor into a second regenerated gas and a lean liquid, and at the same time, the high-temperature second regenerated gas is passed into the first heat exchanger and the high-temperature lean liquid is passed into the second heat exchanger.

[0012] The absorbent storage tank is used to store the carbon dioxide absorbent, and inject the absorbent through the liquid replenishment port to maintain the stability of the absorbent content during continuous operation; the lean liquid pump is used to pump the carbon dioxide absorbent into the carbon dioxide ejector.

[0013] Furthermore, the desorption reactor is heated by using a heater in cooperation with a jacket wrapped around the outer layer of the desorption reactor to realize circulating heating of the heat medium in the jacket or by using a resistance wire wrapped around the outside of the desorption reactor for direct heating, and a spiral baffle device is arranged inside the jacket.

[0014] Furthermore, the absorption reactor is composed of one or more tubular reactors in parallel, with a length of 0.5 to 2.5 m, a nominal diameter of DN8 to DN50, a working pressure of 0.1 to 1.6 MPa, and a working temperature of 10 to 80 ° C. A static mixing element for enhancing the efficient absorption of carbon dioxide is placed in the tubular reactor, and the aspect ratio of the static mixing element is 0.5 to 2.0, the element spacing is 0 to 2.0 times the tube diameter, and the number of elements is 5 to 20. Among them, the pipeline configuration is determined by the partial pressure and flow rate of carbon dioxide, so as to achieve an absorption rate of 99% or more of the low partial pressure carbon dioxide gas entering the pipe at the outlet of the absorption reactor.

[0015] Furthermore, the desorption reactor is composed of one or more tubular reactors with a length of 1 to 3 m, a nominal diameter of DN32 to DN150, a working pressure of 0.1 to 1.6 MPa, and a working temperature of 80 to 200 ° C, and a static mixing element for enhancing the efficient desorption of carbon dioxide is placed in the tubular reactor. The aspect ratio of the static mixing element is 0.5 to 2.0, the element spacing is 0 to 2.0 times the tube diameter, and the number of elements is 5 to 20. At the same time, the outer layer of the desorption reactor is wrapped by a heat exchange jacket and the heat exchange jacket contains a spiral baffle device. Among them, the pipeline configuration is determined by the desorption temperature of the carbon dioxide absorbent to achieve a desorption rate of 99% or more of the rich liquid entering the tube at the outlet of the desorption reactor.

[0016] Another object of the present invention is to provide a tubular parallel-flow carbon dioxide absorption and desorption continuous operation method, which adopts the operating system described in the above embodiment and includes the following steps: S1, injecting carbon dioxide absorbent through the liquid replenishment port of the absorbent storage tank to form a continuous phase in the pipeline.

[0017] S2. A point source low partial pressure carbon dioxide gas is injected into the pipeline from a low partial pressure carbon dioxide inlet through a carbon dioxide injector, so that the gas forms a discrete phase in the pipeline.

[0018] S3. The heat medium inside the jacket wrapped around the outer layer of the desorption reactor is heated to 80-300° C. by a heater, and the heat medium in the jacket is circulated. A spiral baffle device is arranged in the jacket.

[0019] S4. At 0.1-1.6 MPa and 10-80°C, the carbon dioxide absorbent in the absorption reactor fully reacts with the low partial pressure carbon dioxide gas to carry out co-current absorption of carbon dioxide.

[0020] S5. Separate the gas-liquid mixture absorbed by the absorption reactor into purified gas and rich liquid by a first gas-liquid separator. The purified gas refers to the remaining gas after removing carbon dioxide, and the rich liquid refers to the carbon dioxide absorbent that fully absorbs carbon dioxide.

[0021] S6. Preheating the low-temperature rich liquid separated by the first gas-liquid separator by the first heat exchanger with the high-temperature second regeneration gas after desorption. The second regeneration gas refers to high-purity carbon dioxide gas.

[0022] S7, preheating the rich liquid preheated by the first heat exchanger again with the high-temperature lean liquid after desorption by the second heat exchanger, wherein the lean liquid refers to the desorbed carbon dioxide absorbent.

[0023] S8. Use a rich liquid pump to pump the rich liquid preheated by the second heat exchanger into the desorption reactor.

[0024] S9, at 80-300°C, the rich liquid is desorbed in the desorption reactor to produce lean liquid and regenerated gas; the pressure in the desorption reactor is controlled by a pressure controller, and when the pressure exceeds a predetermined value, part of the gas-liquid mixture in the pipe is transported to the second gas-liquid separator. The regenerated gas refers to high-purity carbon dioxide gas.

[0025] S10, separating the delivered gas-liquid mixture into a first regeneration gas and an incomplete desorption liquid by a second gas-liquid separator, and pumping the incomplete desorption liquid into a desorption reactor by a rich liquid pump again. The first regeneration gas refers to high-purity carbon dioxide gas.

[0026] S11. Separating the gas-liquid mixture after passing through the desorption reactor into a second regeneration gas and a lean liquid through a third gas-liquid separator, and simultaneously passing the high-temperature second regeneration gas into a first heat exchanger, and passing the high-temperature lean liquid into a second heat exchanger.

[0027] S12, cooling the high-temperature second regenerated gas after the desorption reactor through the first heat exchanger, cooling the high-temperature lean liquid after the desorption reactor through the second heat exchanger, and recovering the lean liquid to the absorbent storage tank.

[0028] S13. The carbon dioxide absorbent is pumped into the carbon dioxide ejector by a lean liquid pump to achieve the reuse of the carbon dioxide absorbent and complete the tubular parallel flow continuous operation.

[0029] Further, in step S1 , the carbon dioxide absorbent includes any one of an organic phase absorbent, an inorganic phase absorbent, a single type absorbent and a mixed type absorbent.

[0030] Furthermore, in step S2, the low partial pressure carbon dioxide gas refers to a gas with a carbon dioxide partial pressure of 0 to 30%.

[0031] Furthermore, in step S4, the carbon dioxide absorbent and the low partial pressure carbon dioxide gas are transported in parallel.

[0032] Furthermore, in step S12, the first heat exchanger and the second heat exchanger respectively preheat the rich liquid before desorption to 50-100°C and reduce the carbon dioxide absorbent and the second regeneration gas after desorption to 10-80°C through multi-stage waste heat recovery.

[0033] Compared with the prior art, the beneficial technical effects of the present invention are: (1) The tubular parallel-flow carbon dioxide absorption and desorption continuous operation method provided by the present invention adopts continuous operation throughout the whole process, realizes the efficient recycling of carbon dioxide absorbent, effectively reduces the number of carbon capture equipment and the floor space occupied, reduces labor costs and operation risks, improves carbon capture efficiency, and reduces the cost of modification and maintenance of existing equipment, so as to realize the parallel-flow continuous operation of efficient, low-energy consumption and green carbon dioxide absorption and desorption.

[0034] (2) The absorption reactor used for carbon dioxide capture in the present invention effectively increases the specific surface area in the tube by placing a high-efficiency carbon dioxide absorption static mixing element in the tube and connecting multiple stages in parallel, thereby achieving efficient mass transfer, providing the same residence time, improving reaction selectivity and controllability, avoiding the occurrence of incomplete reaction, and being able to efficiently absorb and precisely control low partial pressure and high flux carbon dioxide.

[0035] (3) The desorption reactor used for carbon dioxide desorption of the present invention effectively reduces the desorption heat exchange time, reduces secondary environmental pollution, realizes precise control of desorption efficiency, improves the quality and stability of regenerated gas, and can efficiently desorb high-throughput rich liquid by placing a high-efficiency carbon dioxide desorption static mixing element in the tube, wrapping the outside of the tube with a heat exchange jacket containing a spiral baffle device, and connecting multiple stages in series.

[0036] (4) The present invention recovers and reuses the high heat of the lean liquid and the regenerated gas after carbon dioxide desorption through a heat exchanger in multiple stages to achieve low-temperature rich liquid preheating. The stable heat source provided by continuous operation effectively improves the efficiency of secondary energy utilization, reduces primary energy consumption, reduces the thermal pollution of carbon capture equipment to the environment, and saves carbon capture costs, achieving double energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the connection structure of the tubular parallel-flow carbon dioxide absorption and desorption continuous operation system of the present invention, and the direction of the arrow in the figure indicates the flow direction of the medium.

[0038] Explanation of the reference numerals in the accompanying drawings: low partial pressure carbon dioxide inlet-1; carbon dioxide ejector-2; absorption reactor-3; first gas-liquid separator-4; first heat exchanger-5; second heat exchanger-6; rich liquid pump-7; desorption reactor-8; heater-9; pressure controller-10; second gas-liquid separator-11; third gas-liquid separator-12; absorbent storage tank-13; lean liquid pump-14; purified gas-15; second regeneration gas-16; first regeneration gas-17. DETAILED DESCRIPTION

[0039] Example 1: A tubular parallel-flow carbon dioxide absorption and desorption continuous operation method, such as Figure 1 As shown, the operating system used includes a low partial pressure carbon dioxide inlet 1, a carbon dioxide ejector 2, a tubular multi-stage parallel carbon dioxide absorption reactor (hereinafter referred to as absorption reactor 3), a first gas-liquid separator 4, a first heat exchanger 5, a second heat exchanger 6, a rich liquid pump 7, a tubular multi-stage series carbon dioxide desorption reactor (hereinafter referred to as desorption reactor 8), a heater 9, a pressure controller 10, a second gas-liquid separator 11, a third gas-liquid separator 12, an absorbent storage tank 13 and a lean liquid pump 14.

[0040] The low partial pressure carbon dioxide inlet 1 is connected to the gas phase inlet of the carbon dioxide ejector 2, the outlet of the carbon dioxide ejector 2 is connected to the inlet of the absorption reactor 3, the outlet of the absorption reactor 3 is connected to the inlet of the first gas-liquid separator 4, the liquid phase outlet of the first gas-liquid separator 4 is connected to the first inlet of the first heat exchanger 5, the first outlet of the first heat exchanger 5 is connected to the first inlet of the second heat exchanger 6, the first outlet of the second heat exchanger 6 is connected to the inlet of the rich liquid pump 7, and the outlet of the rich liquid pump 7 is connected to the inlet of the desorption reactor 8.

[0041] The heater 9 is used to provide thermal energy for the desorption reactor 8, the pressure controller 10 is connected to the series pipeline of the desorption reactor 8, the outlet of the pressure controller 10 is connected to the inlet of the second gas-liquid separator 11, the liquid phase outlet of the second gas-liquid separator 11 is connected to the inlet of the rich liquid pump 7, the outlet of the desorption reactor 8 is connected to the inlet of the third gas-liquid separator 12, the gas phase outlet of the third gas-liquid separator 12 is connected to the second inlet of the first heat exchanger 5, the liquid phase outlet of the third gas-liquid separator 12 is connected to the second inlet of the second heat exchanger 6, the second outlet of the second heat exchanger 6 is connected to the inlet of the absorbent storage tank 13, the outlet of the absorbent storage tank 13 is connected to the inlet of the lean liquid pump 14, and the outlet of the lean liquid pump 14 is connected to the liquid phase inlet of the carbon dioxide ejector 2.

[0042] The carbon dioxide ejector 2 is used to inject point source low partial pressure carbon dioxide gas into the pipeline for parallel absorption and desorption, and the point source refers to a fixed emission point; the absorption reactor 3 is used to absorb carbon dioxide from point source low partial pressure carbon dioxide gas from thermal power plants, coal power plants, petrochemical downstream industries and other related industries, and transport the absorbed gas-liquid mixture to the first gas-liquid separator 4.

[0043] The first gas-liquid separator 4 is used to separate the gas-liquid mixture after absorption in the absorption reactor 3 into purified gas 15 and rich liquid; the first heat exchanger 5 uses the high-temperature second regenerated gas 16 after desorption to perform a first preheating of the low-temperature rich liquid separated by the first gas-liquid separator 4, thereby realizing the reuse of waste heat of the second regenerated gas 16; the second heat exchanger 6 uses the high-temperature lean liquid after desorption to perform a second preheating of the rich liquid preheated by the first heat exchanger 5, thereby realizing the reuse of waste heat of the high-temperature lean liquid.

[0044] The rich liquid pump 7 is used to pump the rich liquid after the second preheating into the desorption reactor 8; the desorption reactor 8 is used to heat and desorb the carbon dioxide in the tube through the jacket wrapped in the outer layer of the desorption reactor 8, and transport the desorbed gas-liquid mixture to the third gas-liquid separator 12.

[0045] The pressure controller 10 is used to control the pressure in the desorption reactor 8. When a large amount of carbon dioxide is desorbed and the pressure exceeds a predetermined value, part of the gas-liquid mixture in the pipe is transported to the second gas-liquid separator 11; the second gas-liquid separator 11 is used to separate the gas-liquid mixture transported through the pressure controller 10 into a first regenerated gas 17 (i.e., high-purity carbon dioxide) and an incompletely desorbed liquid, and the incompletely desorbed liquid is pumped into the desorption reactor 8 again through the rich liquid pump 7; the third gas-liquid separator 12 is used to separate the gas-liquid mixture after desorption in the desorption reactor 8 into a second regenerated gas 16 (i.e., high-purity carbon dioxide) and a lean liquid, and at the same time, the high-temperature second regenerated gas 16 is passed into the first heat exchanger 5, and the high-temperature lean liquid is passed into the second heat exchanger 6.

[0046] The absorbent storage tank 13 is used to store the carbon dioxide absorbent, and the lean liquid pump 14 is used to pump the carbon dioxide absorbent into the carbon dioxide ejector 2 .

[0047] In this embodiment, the absorption reactor 3 is a single-branch tubular absorption reactor with a length of 1.5 m and a nominal diameter of DN32. Twelve static mixing elements with a length-to-diameter ratio of 1.5 and an element spacing of 0 for enhancing carbon dioxide absorption are arranged inside the tubular absorption reactor.

[0048] In this embodiment, a single-branch tubular desorption reactor with a length of 1.5m and a nominal diameter of DN80 is selected, and 15 static mixing elements with a length-to-diameter ratio of 1.0 and an element spacing of 20mm are arranged inside the tubular desorption reactor for enhancing the efficient desorption of carbon dioxide; at the same time, the outer layer of the tubular desorption reactor is wrapped by a jacket and the jacket contains a spiral baffle device, and the heating method of the tubular desorption reactor is to use a heater 9 in cooperation with the jacket wrapped around the outer layer of the desorption reactor 8 to realize circulating heating of the heat medium in the jacket.

[0049] The tubular parallel-flow carbon dioxide absorption and desorption continuous operation method of this embodiment comprises the following steps: S1, injecting carbon dioxide absorbent through the liquid replenishing port of the absorbent storage tank 13 to fill the pipeline. In this embodiment, the carbon dioxide absorbent is a mixed solution of monoethanolamine, diethanolamine and triethanolamine (hereinafter referred to as mixed amine absorbent) with a volume ratio of 1:1:1 and a mass fraction of 30%.

[0050] S2. Inject the coal-fired flue gas with a carbon dioxide partial pressure of 15% into the operating system through the carbon dioxide injector 2.

[0051] S3. Circulate the hot water maintained at 95° C. in the heater 9 into the jacket with the spiral baffle device.

[0052] S4. At a pressure and temperature of 0.1 MPa and 40°C respectively, the mixed amine absorbent and the coal-fired flue gas with a carbon dioxide partial pressure of 15% are fully absorbed in the absorption reactor 3, so that the carbon dioxide absorption efficiency reaches 99%.

[0053] S5. Separate the gas-liquid mixture absorbed by the absorption reactor 3 into a purified gas 15 and a rich liquid by the first gas-liquid separator 4; and confirm the absorption efficiency of carbon dioxide in the rich liquid by titration.

[0054] The purified gas 15 refers to the residual gas after removing carbon dioxide, and the rich liquid refers to the mixed amine absorbent that fully absorbs carbon dioxide.

[0055] S6. Preheat the low-temperature rich liquid separated by the first gas-liquid separator 4 to 50° C. through the first heat exchanger 5 using the high-temperature second regeneration gas 16 after desorption.

[0056] S7, the rich liquid preheated by the first heat exchanger 5 is preheated again to 65°C by the second heat exchanger 6 using the high-temperature lean liquid after desorption.

[0057] S8. Use the rich liquid pump 7 to pump the rich liquid preheated by the second heat exchanger 6 into the desorption reactor 8.

[0058] S9. At a temperature of 95°C, the rich liquid is desorbed in the desorption reactor 8 to form a lean liquid (i.e., the mixed amine absorbent after desorption) and regenerated gas (i.e., high-purity carbon dioxide). The pressure in the desorption reactor 8 is controlled by the pressure controller 10. When the pressure exceeds 0.5 MPa, part of the gas-liquid mixture in the pipe is transported to the second gas-liquid separator 11 to reduce the pressure in the desorption reactor 8.

[0059] S10, separating the delivered gas-liquid mixture into the first regenerated gas 17 (i.e., high-purity carbon dioxide) with a purity higher than 99% and the incompletely desorbed liquid through the second gas-liquid separator 11, and pumping the incompletely desorbed liquid back into the desorption reactor 8 through the rich liquid pump 7.

[0060] S11. The gas-liquid mixture after passing through the desorption reactor 8 is separated into a second regenerated gas 16 (i.e., high-purity carbon dioxide) with a purity higher than 99% and a lean liquid by a third gas-liquid separator 12. The desorption efficiency of carbon dioxide in the separated lean liquid is confirmed by titration to reach 99%.

[0061] S12, the second regenerated gas 16 after the desorption reactor 8 is cooled to 40°C through the first heat exchanger 5, the second heat exchanger 6 cools the desorbed lean liquid to 35°C, and the lean liquid is recovered to the absorbent storage tank 13, realizing multi-stage high-efficiency waste heat recovery and reuse.

[0062] S13, using the lean liquid pump 14 to pump the mixed amine absorbent into the carbon dioxide ejector 2, so as to realize the reuse of the mixed amine absorbent and complete the tubular parallel flow continuous operation.

[0063] Example 2: The difference from Example 1 is that: (1) in this example, the carbon dioxide partial pressure in the coal-fired flue gas is 20%, and the carbon dioxide absorbent is a monoethanolamine solution with a mass fraction of 30%.

[0064] (2) In this embodiment, the absorption reactor 3 uses three tubular absorption reactors with a length of 1.0 m and a nominal diameter of DN25, and the three tubular absorption reactors are connected in parallel; 15 static mixing elements with a length-to-diameter ratio of 1.0 and an element spacing of 0 for enhancing carbon dioxide absorption are arranged inside the tubular absorption reactor.

[0065] (3) In this embodiment, four tubular desorption reactors with a length of 2.0 m, a nominal diameter of DN100 and a serpentine arrangement are selected and connected in series; 12 static mixing elements with a length-to-diameter ratio of 1.5 and an element spacing of 10 mm are arranged inside the tubular desorption reactor to enhance the efficient desorption of carbon dioxide.

[0066] (4) The outside of the tubular desorption reactor is wound with a resistance wire, and the tubular desorption reactor is heated by electrically heating the resistance wire through a heater 9, thereby performing direct heating. The surface of the tubular desorption reactor is electrically heated to 130°C.

[0067] In this embodiment, the relative flow rate of gas and liquid is adjusted to achieve carbon dioxide adsorption and desorption efficiency of 99%.

[0068] In summary, the tubular parallel-flow carbon dioxide absorption and desorption continuous operation method provided in Example 1 and Example 2 adopts continuous operation throughout the whole process, realizes the efficient recycling of carbon dioxide absorbent, effectively reduces the number of carbon capture equipment and the floor space occupied, reduces labor costs and operational risks, improves carbon capture efficiency, and reduces the cost of transformation and maintenance of existing equipment, so as to realize the parallel-flow continuous operation of efficient, low-energy consumption, green carbon dioxide absorption and desorption.

[0069] In Example 1 and Example 2, the high heat of the lean liquid and the regenerated gas after carbon dioxide desorption is recovered and reused in multiple stages through a heat exchanger to achieve low-temperature rich liquid preheating. The stable heat source provided by continuous operation effectively improves the secondary energy utilization efficiency, reduces primary energy consumption, reduces the thermal pollution of the carbon capture equipment to the environment, and saves carbon capture costs, achieving double energy saving.

[0070] Test Example 1: Washing Factor It can be used to compare the CO2 absorption efficiency of different reactors. This parameter is used to calculate the number of moles of CO2 removed per mole of absorbent and per unit volume of reactor. The calculation formula is as follows: , where and are the molar flow rates at the inlet and outlet, respectively; is the molar flow rate of the absorbent; is the reactor volume.

[0071] When sodium hydroxide is used as the absorbent, the widely used gas-liquid mass transfer equipment (fixed packed bed, rotating packed bed and bubble column) is selected for comparison with several different types of static mixers (screen type, blade type and spiral type). They are 0.0176-0.173 mol / (mol·L), 0.0508-0.151 mol / (mol·L), 0.0422-0.872 mol / (mol·L), 0.0213-0.528 mol / (mol·L), 0.25-0.563 mol / (mol·L) and 0.267-0.689 mol / (mol·L). It is not difficult to see that tubular static mixing reactors (including mesh static mixers, blade static mixers and spiral static mixers) have excellent removal efficiency in the field of carbon capture and have the potential to become efficient gas absorption equipment.

[0072] Test Example 2: The volumetric mass transfer coefficient is the main parameter for evaluating the efficiency of the reactor. The gas-liquid mass transfer equipment with strong practicality (bubble tower, mechanical stirring tank, packed tower) was selected for comparison with the typical static mixer (screen type static mixer). The volumetric mass transfer coefficients of the bubble tower, mechanical stirring tank, packed tower and screen type static mixer in the physical absorption of carbon dioxide in reverse osmosis water are 0.2 to 17×10 -3 / s, 4.2~55.4×10 -3 / s, 10~12×10 -3 / s and 50~830×10 -3 / s. Under the condition of similar specific energy consumption, the volume mass transfer coefficient of tubular static mixing reactor (including mesh static mixer) increases much faster with the increase of gas flow rate than that of traditional reactor, and the total volume mass transfer coefficient increases by several orders of magnitude.

[0073] By comparing Test Example 1 and Test Example 2 with other traditional tower equipment and some process intensification equipment, it is shown that the tubular desorption reactor and tubular absorption reactor used in Example 1 and Example 2 can reduce costs and increase efficiency compared with other equipment. At the same time, the tubular desorption reactor and tubular absorption reactor are essentially tubular static mixing reactors, that is, carbon dioxide desorption and absorption are achieved by adding different types of static mixing elements in the tubular reactor.

[0074] The absorption reactor 3 used for carbon dioxide capture in Example 1 and Example 2 effectively increases the specific surface area in the tube by placing a high-efficiency carbon dioxide absorption static mixing element in the tube and multi-stage parallel connection, thereby achieving efficient mass transfer, providing the same residence time, improving reaction selectivity and controllability, avoiding the occurrence of incomplete reaction, and being able to efficiently absorb and accurately control low partial pressure and high flux carbon dioxide.

[0075] Similarly, the desorption reactor 8 used for carbon dioxide desorption in Example 1 and Example 2 effectively reduces the desorption heat exchange time, reduces secondary environmental pollution, achieves precise control of desorption efficiency, improves the quality and stability of regenerated gas, and can efficiently desorb high-throughput rich liquid by placing a high-efficiency carbon dioxide desorption static mixing element in the tube, wrapping the outside of the tube with a heat exchange jacket containing a spiral baffle device, and connecting multiple stages in series.

[0076] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A tubular parallel-flow carbon dioxide absorption and desorption continuous operation system, characterized in that: It includes a low partial pressure carbon dioxide inlet, a carbon dioxide ejector, an absorption reactor, a first gas-liquid separator, a first heat exchanger, a second heat exchanger, a rich liquid pump, a desorption reactor, a heater, a pressure controller, a second gas-liquid separator, a third gas-liquid separator, an absorbent storage tank and a lean liquid pump; The low partial pressure carbon dioxide inlet is connected to the gas phase inlet of the carbon dioxide ejector, the outlet of the carbon dioxide ejector is connected to the inlet of the absorption reactor, the outlet of the absorption reactor is connected to the inlet of the first gas-liquid separator, the liquid phase outlet of the first gas-liquid separator is connected to the first inlet of the first heat exchanger, the first outlet of the first heat exchanger is connected to the first inlet of the second heat exchanger, the first outlet of the second heat exchanger is connected to the inlet of the rich liquid pump, and the outlet of the rich liquid pump is connected to the inlet of the desorption reactor; The heater is used to provide thermal energy for the desorption reactor, the pressure controller is connected to the series pipeline of the desorption reactor, the outlet of the pressure controller is connected to the inlet of the second gas-liquid separator, the liquid phase outlet of the second gas-liquid separator is connected to the inlet of the rich liquid pump, the outlet of the desorption reactor is connected to the inlet of the third gas-liquid separator, the gas phase outlet of the third gas-liquid separator is connected to the second inlet of the first heat exchanger, the liquid phase outlet of the third gas-liquid separator is connected to the second inlet of the second heat exchanger, the second outlet of the second heat exchanger is connected to the inlet of the absorbent storage tank, the outlet of the absorbent storage tank is connected to the inlet of the lean liquid pump, and the outlet of the lean liquid pump is connected to the liquid phase inlet of the carbon dioxide ejector.

2. The tubular parallel-flow carbon dioxide absorption and desorption continuous operation system according to claim 1, characterized in that: The carbon dioxide ejector is used to eject point-source low-partial-pressure carbon dioxide gas into the pipeline for parallel-flow absorption and desorption; The absorption reactor is used to absorb carbon dioxide and transport the absorbed gas-liquid mixture to the first gas-liquid separator; The first gas-liquid separator is used to separate the gas-liquid mixture absorbed by the absorption reactor into purified gas and rich liquid; The first heat exchanger uses the second regenerated gas after desorption to preheat the rich liquid separated by the first gas-liquid separator for the first time; The second heat exchanger uses the desorbed lean liquid to preheat the rich liquid preheated by the first heat exchanger for a second time; The rich liquid pump is used to pump the rich liquid after the second preheating into the desorption reactor; The desorption reactor is used to heat and desorb the carbon dioxide in the tube, and transport the desorbed gas-liquid mixture to the third gas-liquid separator; The pressure controller is used to control the pressure in the desorption reactor, and when a large amount of carbon dioxide is desorbed and the pressure exceeds a predetermined value, part of the gas-liquid mixture in the tube is transported to the second gas-liquid separator; The second gas-liquid separator is used to separate the gas-liquid mixture delivered by the pressure controller into the first regeneration gas and the incomplete desorption liquid, and pump the incomplete desorption liquid into the desorption reactor again through the rich liquid pump; The third gas-liquid separator is used to separate the gas-liquid mixture after desorption by the desorption reactor into a second regeneration gas and a lean liquid, and at the same time, the second regeneration gas is passed into the first heat exchanger and the lean liquid is passed into the second heat exchanger; The absorbent storage tank is used to store the carbon dioxide absorbent, and the carbon dioxide absorbent is injected through the liquid replenishment port to maintain the stability of the carbon dioxide absorbent content during continuous operation; The lean liquid pump is used to pump the carbon dioxide absorbent into the carbon dioxide ejector.

3. The tubular parallel-flow carbon dioxide absorption and desorption continuous operation system according to claim 2, characterized in that: The desorption reactor is heated by using a heater in cooperation with a jacket wrapped around the outer layer of the desorption reactor to realize circulating heating of the heat medium in the jacket or by using a resistance wire wound around the outside of the desorption reactor for direct heating, and a spiral baffle device is arranged inside the jacket.

4. The tubular parallel-flow carbon dioxide absorption and desorption continuous operation system according to claim 3, characterized in that: The absorption reactor is composed of one or more tubular reactors connected in parallel, with a length of 0.5 to 2.5 m, a nominal diameter of DN8 to DN50, a working pressure of 0.1 to 1.6 MPa, and a working temperature of 10 to 80° C. A static mixing element for enhancing efficient absorption of carbon dioxide is placed in the tubular reactor, and the aspect ratio of the static mixing element is 0.5 to 2.0, the element spacing is 0 to 2.0 times the tube diameter, and the number of elements is 5 to 20; The pipeline configuration is determined by the partial pressure and flow rate of carbon dioxide, so as to achieve an absorption rate of 99% or more at the outlet of the absorption reactor of the low partial pressure carbon dioxide gas entering the pipe.

5. The tubular parallel-flow carbon dioxide absorption and desorption continuous operation system according to claim 4, characterized in that: The desorption reactor is composed of one or more tubular reactors connected in series, with a length of 1 to 3 m, a nominal diameter of DN32 to DN150, a working pressure of 0.1 to 1.6 MPa, and a working temperature of 80 to 200° C. A static mixing element for enhancing efficient desorption of carbon dioxide is placed in the tubular reactor, the aspect ratio of the static mixing element is 0.5 to 2.0, the element spacing is 0 to 2.0 times the tube diameter, and the number of elements is 5 to 20. At the same time, the outer layer of the desorption reactor is wrapped by a jacket and the jacket contains a spiral baffle device; Among them, the pipeline configuration is determined by the desorption temperature of the carbon dioxide absorbent, so as to achieve a desorption rate of 99% or more of the rich liquid entering the pipe at the outlet of the desorption reactor.

6. A tubular parallel-flow carbon dioxide absorption and desorption continuous operation method, characterized in that: The tubular parallel-flow carbon dioxide absorption and desorption continuous operation system according to any one of claims 1 to 5 comprises the following steps: S1. Inject carbon dioxide absorbent through the liquid replenishment port of the absorbent storage tank to make it a continuous phase in the pipeline; S2, injecting point source low partial pressure carbon dioxide gas from the low partial pressure carbon dioxide inlet into the pipeline through a carbon dioxide injector, so that it constitutes a discrete phase in the pipeline; S3, heating the heat medium inside the jacket wrapped around the outer layer of the desorption reactor to 80-300° C. by a heater, and realizing the circulation of the heat medium in the jacket, and a spiral baffle device is arranged in the jacket; S4, at 0.1-1.6 MPa and 10-80° C., the carbon dioxide absorbent in the absorption reactor fully reacts with the low partial pressure carbon dioxide gas to perform carbon dioxide co-current absorption; S5, separating the gas-liquid mixture absorbed by the absorption reactor into purified gas and rich liquid by a first gas-liquid separator; S6, preheating the rich liquid separated by the first gas-liquid separator by using the second regenerated gas after desorption through the first heat exchanger; S7, preheating the rich liquid preheated by the first heat exchanger again by using the lean liquid after desorption through the second heat exchanger; S8, using a rich liquid pump to pump the rich liquid preheated by the second heat exchanger into a desorption reactor; S9, at 80-300°C, the rich liquid is desorbed in the desorption reactor to produce lean liquid and regenerated gas; the pressure in the desorption reactor is controlled by a pressure controller, and when the pressure exceeds a predetermined value, part of the gas-liquid mixture in the tube is transported to the second gas-liquid separator; S10, separating the delivered gas-liquid mixture into a first regeneration gas and an incomplete desorption liquid by a second gas-liquid separator, and pumping the incomplete desorption liquid into a desorption reactor by a rich liquid pump again; S11, separating the gas-liquid mixture after passing through the desorption reactor into a second regeneration gas and a lean liquid through a third gas-liquid separator, and simultaneously passing the second regeneration gas into a first heat exchanger, and passing the lean liquid into a second heat exchanger; S12, cooling the second regenerated gas after the desorption reactor through the first heat exchanger, cooling the lean liquid after the desorption reactor through the second heat exchanger, and recovering the lean liquid to the absorbent storage tank; S13. The carbon dioxide absorbent is pumped into the carbon dioxide ejector by a lean liquid pump to achieve the reuse of the carbon dioxide absorbent and complete the tubular parallel flow continuous operation.

7. The tubular parallel-flow carbon dioxide absorption and desorption continuous operation method according to claim 6, characterized in that: In step S1 , the carbon dioxide absorbent includes any one of an organic phase absorbent, an inorganic phase absorbent, a single type absorbent, and a mixed type absorbent.

8. The tubular parallel-flow carbon dioxide absorption and desorption continuous operation method according to claim 7, characterized in that: In step S2, the low partial pressure carbon dioxide gas refers to a gas having a carbon dioxide partial pressure of 0 to 30%.

9. The tubular parallel-flow carbon dioxide absorption and desorption continuous operation method according to claim 8, characterized in that: In step S4, the carbon dioxide absorbent and the low partial pressure carbon dioxide gas are transported in parallel flow.

10. The tubular parallel-flow carbon dioxide absorption and desorption continuous operation method according to claim 9, characterized in that: In step S12, the first heat exchanger and the second heat exchanger respectively preheat the rich liquid before desorption to 50-100°C and reduce the carbon dioxide absorbent and the second regeneration gas after desorption to 10-80°C through multi-stage waste heat recovery.

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