Flue gas carbon dioxide capturing and regenerating system based on bi-component secondary amine

Abstract

The invention relates to a flue gas carbon dioxide capture and regeneration system based on bi-component secondary amine, which comprises an absorption tower, a separator, a mixing tank, a lean and rich liquid heat exchanger and a regeneration mechanism, a flue gas inlet and a rich liquid outlet of the absorption tower are respectively connected with a CO2 gas source pipeline and an inlet of the separator; an upper barren liquor outlet and a lower rich liquor outlet of the separator are respectively connected with a first inlet of the mixing tank and a first inlet of the barren and rich liquor heat exchanger, a first outlet of the barren and rich liquor heat exchanger is used for conveying the rich liquor after heat exchange to the regeneration mechanism, and a regenerated barren liquor outlet of the regeneration mechanism is connected with a second inlet of the barren and rich liquor heat exchanger; a second outlet of the barren-rich liquid heat exchanger is connected with a second inlet of the mixing tank; an outlet of the mixing tank is used for conveying the mixed barren liquid into the absorption tower; the absorption tower is filled with an absorbent in advance, and the absorbent is a two-component secondary amine solution composed of diethylamine, N-ethyl isopropylamine and water. The problem that energy consumption is high in the smoke carbon dioxide trapping and regenerating process can be effectively solved.

Description

Technical Field

[0001] The present invention relates to CO 2 The field of capture technology particularly relates to a flue gas carbon dioxide capture and regeneration system based on a two-component secondary amine. Background Art

[0002] With the rapid development of economy, a large amount of CO 2 The emission of carbon dioxide has caused a series of serious environmental problems, such as greenhouse effect, sea level rise and frequent occurrence of extreme weather. Despite the rapid development of renewable energy, energy consumption will still be dominated by fossil energy in the next few decades.

[0003] Currently, amine-based chemical absorption is the most effective CO 2 However, its further development is limited by the high CO 2 Limitation of high energy consumption during solution regeneration: Studies have shown that the regeneration heat load of the solution accounts for 70% of the total energy consumption, which is high in energy consumption. Summary of the invention

[0004] The purpose of the present invention is to provide a flue gas carbon dioxide capture and regeneration system based on a two-component secondary amine, which can effectively solve the problem of high energy consumption in the flue gas carbon dioxide capture and regeneration process.

[0005] The object of the present invention is achieved by providing a flue gas carbon dioxide capture and regeneration system based on a two-component secondary amine, comprising an absorption tower, a separator, a mixing tank, a lean-rich liquid heat exchanger and a regeneration mechanism; the flue gas inlet and the rich liquid outlet of the absorption tower are respectively used to connect the CO 2 The gas source pipeline and the inlet of the separator, the upper lean liquid outlet and the lower rich liquid outlet of the separator are respectively used to connect the first inlet of the mixing tank and the first inlet of the lean-rich liquid heat exchanger, the first outlet of the lean-rich liquid heat exchanger is used to transport the rich liquid after heat exchange to the regeneration mechanism, the regenerated lean liquid outlet of the regeneration mechanism is used to connect the second inlet of the lean-rich liquid heat exchanger, the second outlet of the lean-rich liquid heat exchanger is used to connect the second inlet of the mixing tank, and the outlet of the mixing tank is used to transport the mixed lean liquid to the absorption tower; wherein the absorption tower is pre-installed with an absorbent, and the absorbent is a two-component secondary amine solution composed of diethylamine, N-ethylisopropylamine and water.

[0006] In a preferred embodiment of the present invention, the mass ratio of diethylamine to N-ethylisopropylamine is (60-70):(20-30), and the total amine concentration of the two-component secondary amine solution is 1-2 mol / L.

[0007] In a preferred embodiment of the present invention, the regeneration mechanism includes a regeneration tower and a reboiler, the reboiler is connected to the bottom of the regeneration tower, the first outlet of the lean and rich liquid heat exchanger is connected to the corresponding inlet of the reboiler through a corresponding pipeline, the reflux port of the reboiler is connected to the lower part of the regeneration tower through a corresponding pipeline, the bottom of the regeneration tower is also connected to the reboiler through a corresponding pipeline, and the regeneration lean liquid outlet is arranged at the bottom of the reboiler.

[0008] In a preferred embodiment of the present invention, both the absorption tower and the regeneration tower are packed tower structures, and a plurality of packing layers spaced apart from each other are provided in the packed tower structure, and the packing layers are corrugated metal perforated plates.

[0009] In a preferred embodiment of the present invention, the flue gas carbon dioxide capture and regeneration device based on two-component secondary amines further comprises a regeneration gas cooler, the regeneration gas outlet at the top of the regeneration tower is used to connect to the inlet of the regeneration gas cooler, the condensate outlet of the regeneration gas cooler is used to reflux the condensate into the regeneration tower, and the gas outlet of the regeneration gas cooler is used to connect to the CO 2 Discharge line.

[0010] In a preferred embodiment of the present invention, a first heat exchanger is further provided on the rich liquid pipeline between the lower rich liquid outlet of the separator and the first inlet of the lean-rich liquid heat exchanger, for exchanging heat between the regenerated gas at the regenerated gas outlet at the top of the regeneration tower and the upper rich liquid in the rich liquid pipeline, and the regenerated gas after heat exchange is then transported to the regenerated gas cooler.

[0011] In a preferred embodiment of the present invention, the flue gas carbon dioxide capture and regeneration device based on two-component secondary amines also includes a water scrubbing tower, the flue gas outlet at the top of the absorption tower is used to connect to the flue gas inlet of the water scrubbing tower, the water washing liquid outlet of the water scrubbing tower is used to return the water washing liquid to the absorption tower, and the flue gas exhaust port of the water scrubbing tower is used to connect to the decarbonization flue gas exhaust pipeline.

[0012] In a preferred embodiment of the present invention, a second heat exchanger is also provided on the rich liquid pipeline for exchanging heat between the flue gas at the flue gas outlet at the top of the absorption tower and the upper rich liquid in the rich liquid pipeline, and the flue gas after heat exchange is then transported to the water washing tower.

[0013] In a preferred embodiment of the present invention, the mixing tank is also connected to a replenishing liquid pipeline for replenishing N-ethylisopropylamine; a lean liquid cooler is also provided on the pipeline between the outlet of the mixing tank and the absorbent inlet of the absorption tower.

[0014] In a preferred embodiment of the present invention, the mixing tank comprises a metal tank body, the outer side of the metal tank body is wrapped with a heat-insulating material layer, an agitator is arranged inside the metal tank body, and a plurality of guide plates are circumferentially spaced on the inner wall of the metal tank body.

[0015] As described above, the system of the present invention adopts a two-component secondary amine solution composed of diethylamine, N-ethylisopropylamine and water as the absorbent. Diethylamine has a shorter carbon chain structure, which can reduce its reaction heat, and the steric hindrance effect of N-ethylisopropylamine can reduce the overall reaction heat. The two work together to achieve low energy consumption absorption; thus, CO can be absorbed in the absorption tower. 2 The reaction and the desorption of CO in the regeneration mechanism 2 In the reaction, the reaction heat can be effectively reduced, thereby effectively reducing the regeneration energy consumption. Combined with the heat exchange effect of the lean and rich liquid heat exchanger, the energy consumption can be further reduced, which is more conducive to energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The following drawings are only intended to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0017] in:

[0018] Figure 1 A schematic diagram of the structure of a flue gas carbon dioxide capture and regeneration system based on a two-component secondary amine provided by the present invention.

[0019] Figure 2 This is a data graph of the regeneration efficiency when testing with different absorbents.

[0020] Description of Figure Numbers:

[0021] 1. Absorption tower; 11. CO 2 Gas source pipeline;

[0022] 2. Separator; 21. Rich liquid pipeline; 22. Pressure pump;

[0023] 3. Mixing tank; 31. Lean liquid cooler; 32. Make-up liquid pipeline;

[0024] 4. Lean and rich liquid heat exchanger;

[0025] 5. Regeneration tower;

[0026] 6. Reboiler;

[0027] 7. Regeneration gas cooler; 71. CO 2 Discharge pipe;

[0028] 8. Water washing tower; 81. Decarbonization flue gas emission pipeline. DETAILED DESCRIPTION

[0029] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0030] like Figure 1As shown, the present application provides a flue gas carbon dioxide capture and regeneration system based on a two-component secondary amine, comprising an absorption tower 1, a separator 2, a mixing tank 3, a lean-rich liquid heat exchanger 4 and a regeneration mechanism.

[0031] The flue gas inlet and rich liquid outlet of the absorption tower 1 are respectively used to connect the CO 2 The gas source pipeline 11 and the inlet of the separator 2, the upper lean liquid outlet and the lower rich liquid outlet of the separator 2 are respectively used to connect the first inlet of the mixing tank 3 and the first inlet of the lean-rich liquid heat exchanger 4, the first outlet of the lean-rich liquid heat exchanger 4 is used to transport the rich liquid after heat exchange to the regeneration mechanism, the regenerated lean liquid outlet of the regeneration mechanism is used to connect the second inlet of the lean-rich liquid heat exchanger 4, the second outlet of the lean-rich liquid heat exchanger 4 is used to connect the second inlet of the mixing tank 3, and the outlet of the mixing tank 3 is used to transport the mixed lean liquid to the absorption tower 1; wherein the absorption tower 1 is pre-installed with an absorbent, and the absorbent is a two-component secondary amine solution composed of diethylamine, N-ethylisopropylamine and water.

[0032] The molecular formula of the above diethylamine is C 4 H 11 N, English name is Diethylamine, English abbreviation is DETN; N-ethylisopropylamine can also be called N-ethylisopropylamine, molecular formula is C 5 H 13 N, English name is N-ethylpropan-2-amine, English abbreviation is EIPA; both substances are existing substances.

[0033] Existing research mainly focuses on reducing sensible heat and vaporization heat through anhydrous absorbents and phase change absorbents, such as reducing sensible heat by 12.2%-18.9% through ionic liquids and reducing sensible heat and latent heat by 75%-80% through phase change agents, but there is still high energy consumption. Regeneration energy consumption (Qtot) includes three parts: reaction heat (Qrea), sensible heat (Qsen) and latent heat of vaporization (Qvap). In this application, the regeneration energy consumption is reduced from the perspective of reducing reaction heat. The above-mentioned DETN / EIPA two-component secondary amine solution is used, diethylamine is used as the main absorbent, and N-ethylisopropylamine is used as a co-absorbent. The secondary amine in the solution can have a lower reaction heat due to the characteristics of the molecular structure, which can effectively reduce the reaction heat and reduce energy consumption.

[0034] When working, CO 2 The gas source pipeline 11 is used to transfer CO 2 The gas source (e.g. desulfurized flue gas) is transported to the absorption tower 1 through the flue gas inlet at the bottom of the absorption tower 1. The absorption tower 1 is used to convert CO 2 CO in the gas source 2The reactant (also called lean liquid) reacts to generate an absorption rich liquid. The generated absorption rich liquid enters the separator 2 through the rich liquid outlet at the bottom of the absorption tower 1. The separator 2 can separate the rich liquid and the unreacted lean liquid in the absorption rich liquid. The upper lean liquid after separation enters the mixing tank 3, and the lower rich liquid enters the regeneration mechanism after passing through the lean-rich liquid heat exchanger 4. The lower rich liquid entering the regeneration mechanism desorbs CO in the regeneration mechanism. 2 After the reaction, a regenerated lean liquid is generated, and the generated regenerated lean liquid enters the mixing tank 3 after passing through the lean-rich liquid heat exchanger 4. The lean liquid mixed in the mixing tank 3 then enters the absorption tower 1. The lean-rich liquid heat exchanger 4 can perform heat exchange between the rich liquid from the bottom of the absorption tower 1 and the regenerated lean liquid from the regeneration mechanism to increase the temperature of the absorption rich liquid and reduce the temperature of the regenerated lean liquid.

[0035] Therefore, the system of the present application adopts a two-component secondary amine solution composed of diethylamine, N-ethylisopropylamine and water as the absorbent. The shorter carbon chain structure of diethylamine can make its reaction heat lower (about 51.19 kJ / mol), while the steric hindrance effect of N-ethylisopropylamine can reduce the overall reaction heat. The synergistic effect of the two can achieve low energy consumption absorption; thus, CO can be absorbed in the absorption tower 1. 2 The reaction and the desorption of CO in the regeneration mechanism 2 In the reaction, the reaction heat can be effectively reduced, thereby effectively reducing the regeneration energy consumption. In addition, the heat exchange effect of the lean and rich liquid heat exchanger 4 can further reduce the energy consumption, which is more conducive to energy saving.

[0036] In a specific embodiment, the mass ratio of diethylamine to N-ethylisopropylamine is (60-70):(20-30), and the total amine concentration of the two-component secondary amine solution is 1-2 mol / L. The mass ratio of diethylamine to N-ethylisopropylamine is further preferably 70:30, which has the best effect and can reduce the reaction heat.

[0037] Reference Figure 1 The regeneration mechanism includes a regeneration tower 5 and a reboiler 6. The reboiler 6 is connected to the bottom of the regeneration tower 5. The first outlet of the lean-rich liquid heat exchanger 4 is connected to the corresponding inlet of the reboiler 6 through a corresponding pipeline. The reflux port of the reboiler 6 is connected to the lower part of the regeneration tower 5 through a corresponding pipeline. The bottom of the regeneration tower 5 is also connected to the reboiler 6 through a corresponding pipeline. The regeneration lean liquid outlet is arranged at the bottom of the reboiler 6.

[0038] When in use, the lower layer of rich liquid separated by the separator 2 enters the reboiler 6 after passing through the lean-rich liquid heat exchanger 4. The reboiler 6 can vaporize the transported lower layer of rich liquid, and the vaporized two-phase flow is sent back to the regeneration tower 5 through the reflux port. The gaseous phase component in the returned tower passes upward through the tower plate, while the liquid phase component falls back to the bottom of the tower and enters the reboiler 6 to continue vaporization; it is also regenerated during the vaporization process, so that the rich liquid becomes lean liquid, and the regeneration effect can be better after the vaporization of the reboiler 6. After the regenerated lean liquid flows out of the reboiler 6, it enters the lean-rich liquid heat exchanger 4, and can exchange heat with the upper layer of rich liquid to achieve the recovery and utilization of waste heat.

[0039] The regeneration tower 5 adopts a segmented heating method, including a reflux heating section at the top of the tower, a direct heating section in the middle of the tower, and a reboiling section at the bottom of the tower, wherein the reflux heating utilizes the sensible heat of the lean liquid, the direct heating utilizes medium-pressure steam, and the reboiling utilizes low-pressure steam. The temperature gradient control realizes the graded utilization of energy and reduces the regeneration energy consumption. The above-mentioned regeneration tower 5 can also be called a fractionation tower, and its specific structure is an existing structure, which will not be repeated here.

[0040] The absorption tower 1 and the regeneration tower 5 are preferably packed tower structures, in which a plurality of packing layers are arranged in an upper and lower interval, and the packing layers are corrugated metal perforated plates. Since the absorption rate of the two-component secondary amine solution is relatively low, the packing layer is a corrugated plate, which can increase the specific surface area and effectively improve the reaction rate.

[0041] The specific surface area of ​​the metal perforated plate is preferably not less than 500m 2 / m 3 , porosity greater than 95%, pressure drop does not exceed 100Pa / m. A high-efficiency demister can also be installed at the top of the tower to reduce amine liquid entrainment, and a liquid level meter and temperature sensor can also be installed at the bottom of the tower to monitor operating parameters in real time.

[0042] The above-mentioned separator 2 mainly utilizes the difference between hydrophilicity and hydrophobicity to separate the rich liquid and the lean liquid in the absorbed rich liquid, with the lean liquid located in the upper layer and the rich liquid located in the lower layer after separation; the separator 2 can specifically adopt a membrane structure to achieve the separation function, or other structures can be adopted.

[0043] The above-mentioned lean and rich liquid heat exchanger 4 can adopt any heat exchanger as needed. For example, in the present embodiment, the lean and rich liquid heat exchanger 4 adopts a composite plate structure, and the heat exchange efficiency is not less than 90%. The temperature difference of the lean and rich liquid heat exchanger 4 is less than 10°C. It includes a main heat exchange zone and an enhanced heat exchange zone. The main heat exchange zone adopts ordinary plates, and the enhanced heat exchange zone adopts enhanced plates with vortex generators to reduce flow resistance while ensuring heat exchange efficiency. The area of ​​the enhanced plates accounts for 30-40%, and the spacing between the plates is 3-5mm.

[0044] Generally, a booster pump 22 is provided on the rich liquid pipeline 21 between the lower outlet of the separator 2 and the first inlet of the lean-rich liquid heat exchanger 4 , so as to pump the lower rich liquid into the regeneration tower 5 .

[0045] Furthermore, the flue gas carbon dioxide capture and regeneration device based on two-component secondary amines also includes a regeneration gas cooler 7, the regeneration gas outlet at the top of the regeneration tower 5 is used to connect to the inlet of the regeneration gas cooler 7, the condensate outlet of the regeneration gas cooler 7 is used to reflux the condensate into the regeneration tower 5, and the gas outlet of the regeneration gas cooler 7 is used to connect to the CO 2 Discharge line 71.

[0046] The flue gas carbon dioxide capture and regeneration device based on two-component secondary amine also includes a water scrubbing tower 8. The flue gas outlet at the top of the absorption tower 1 is used to connect to the flue gas inlet of the water scrubbing tower 8. The washing liquid outlet of the water scrubbing tower 8 is used to return the washing liquid to the absorption tower 1. The flue gas discharge port of the water scrubbing tower 8 is used to connect to the decarbonization flue gas discharge pipeline 81.

[0047] The structures of the regenerator cooler and the water washing tower 8 are also existing structures. The condensate flowing out of the condensate outlet of the regeneration gas cooler 7 is returned to the regeneration tower 5 again, and the volatilized amine and water can be recovered; the water washing liquid flowing out of the water washing liquid outlet of the water washing tower 8 is returned to the absorption tower 1 again, and the amine and water in the flue gas can be recovered.

[0048] In an optional embodiment, a closed circulating water system can be set between the water washing tower 8 and the absorption tower 1, including a circulating water pump, a plate heat exchanger and a temperature regulating valve, and the top temperature of the absorption tower 1 can be controlled by adjusting the circulating water temperature, wherein the heat exchange area of ​​the plate heat exchanger is 20-30m 2 / MW processing capacity, the circulating water flow rate is 1.5-2 times the gas flow rate.

[0049] Preferably, a first heat exchanger is provided on the rich liquid pipeline 21 between the lower rich liquid outlet of the separator 2 and the first inlet of the lean-rich liquid heat exchanger 4, for heat exchange between the regenerated gas at the regenerated gas outlet at the top of the regeneration tower 5 and the upper rich liquid in the rich liquid pipeline 21, and the regenerated gas after heat exchange is then transported to the regenerated gas cooler 7. A second heat exchanger is also provided on the rich liquid pipeline 21, for heat exchange between the flue gas at the flue gas outlet at the top of the absorption tower 1 and the upper rich liquid in the rich liquid pipeline 21, and the flue gas after heat exchange is then transported to the water scrubber 8.

[0050] Thus, the present application adopts a three-stage heat exchange network design. The first stage of heat exchange is at the lean-rich liquid heat exchanger 4, which is used to exchange heat between the rich liquid from the absorber 1 and the regenerated lean liquid from the reboiler 6; the second stage of heat exchange is the heat exchange between the waste heat of the regenerated gas at the top of the regeneration tower 5 and the upper layer of the rich liquid in the rich liquid pipeline 21; the third stage of heat exchange is the heat exchange between the waste heat of the flue gas at the top of the absorber 1 and the upper layer of the rich liquid in the rich liquid pipeline 21; the cascade utilization of the system waste heat is realized, and the waste heat is fully recovered to reduce energy consumption. Among them, each stage of the heat exchanger adopts a countercurrent heat exchange method, and a bypass regulating valve can be set for temperature control.

[0051] As needed, the entire system can also be equipped with an intelligent heat control system, including temperature sensors, flow meters, control valves and PLC controllers to achieve coordinated and optimized operation of each heat exchange unit. The temperature measurement accuracy is ±0.1°C, the flow measurement accuracy is ±1%, and the control valve is electrically adjusted.

[0052] Since the N-ethylisopropylamine may be decomposed or lost during the entire reaction process, the mixing tank 3 is also connected to a replenishing liquid pipeline 32 as needed to replenish the N-ethylisopropylamine to ensure the effect.

[0053] Generally, a lean liquid cooler 31 is provided on the pipeline between the outlet of the mixing tank 3 and the absorbent inlet of the absorption tower 1 to cool the lean liquid and improve the absorption performance.

[0054] Furthermore, the mixing tank 3 includes a metal tank body, the outer side of the metal tank body is wrapped with a heat-insulating material layer, an agitator is arranged inside the metal tank body, and a plurality of guide plates are circumferentially spaced on the inner wall of the metal tank body.

[0055] The metal tank body may be a stainless steel tank body, for example, and the number of guide plates may be four, for example, and the plate surface may be arranged vertically. The mixing tank 3 has a heat buffer function, and adopts a double-layer insulation structure design, with an inner layer of stainless steel and an outer layer of insulation material. An agitator and a guide plate are arranged in the tank to balance the temperature fluctuation of the system, wherein the thickness of the insulation material layer is 80-100 mm, so as to control the heat loss rate to less than 5%.

[0056] In a specific embodiment, the system is mainly composed of three core modules: absorption system, regeneration system and heat integration system. The absorption tower 1 adopts a packed tower structure with a diameter of 2.5m and a height of 15m, and is filled with regular metal perforated plate corrugated packing with a specific surface area of ​​550m 2 / m 3, the void ratio is 97%, and the pressure drop is 85Pa / m. A wire mesh demister is installed on the top of the tower, and the demister efficiency is ≥99%. The bottom of the tower is equipped with a magnetic float level gauge and a PT100 temperature sensor. Regeneration tower 5 adopts a packed tower structure with a diameter of 2m and a height of 12m, and the packing specifications are the same as those of absorption tower 1. Regeneration tower 5 adopts a segmented heating method. The top reflux heating section uses the sensible heat of the lean liquid (40-50℃), the direct heating section in the tower uses 0.3MPa medium-pressure steam (90-100℃), and the reboiling section at the bottom of the tower uses 0.15MPa low-pressure steam (105-115℃). The heat integration system adopts a three-stage heat exchange network design; the first stage of heat exchange is the lean and rich liquid heat exchanger 4, and the lean and rich liquid heat exchanger 4 adopts a plate heat exchanger structure with a heat exchange area of ​​200m 2 , including the main heat exchange zone and the enhanced heat exchange zone; the main heat exchange zone uses ordinary V-shaped plates, and the enhanced heat exchange zone uses enhanced plates with semi-elliptical vortex generators. The area of ​​the enhanced plates accounts for 35%, the spacing between the plates is 4mm, and the heat exchange efficiency reaches 92%. The second stage of heat exchange is the heat exchange between the regenerated gas at the top of the regeneration tower 5 and the lower layer of rich liquid in the rich liquid pipeline 21. The inlet temperature of the regenerated gas is 105℃, the outlet temperature is 40℃, and the preheating temperature of the lower layer of rich liquid is increased by 15-20℃. The third stage of heat exchange is the heat recovery of the flue gas at the top of the absorption tower 1. A closed circulating water system is used. The circulating water flow rate is 1.8 times the gas flow rate. The heat exchange area of ​​the plate heat exchanger is 25m 2 / MW processing capacity.

[0057] The mixing tank 3 adopts a double-layer insulation structure, with the inner layer being 316L stainless steel (wall thickness 6mm) and the outer layer being polyurethane foam insulation material (thickness 90mm). A built-in agitator (speed 60r / min) and four guide plates arranged at 90° are used to achieve temperature homogenization, and the heat loss rate is controlled at 4.2%. The entire system is equipped with an intelligent heat control system, including a PT100 temperature sensor (accuracy ±0.1℃), an electromagnetic flowmeter (accuracy ±1%, measuring range 5-50m3 / h) and an electric control valve (adjustment accuracy 0.5%), and a Siemens S7-1200 series PLC controller (control cycle 100ms) is used to achieve precise control. DETN / EIPA two-component secondary amine is used as the absorbent in absorption tower 1, with a mass ratio of 70:30 and a total amine concentration of 1.5mol / L. The DETN reaction heat is 51.19kJ / mol, the overall reaction heat of the mixed solution is 54.32kJ / mol, and CO 2 Absorption capacity 0.85 mol CO 2 / mol amine, regeneration temperature 105-115℃.

[0058] In this embodiment, the overall operating parameters of the system are: processing capacity 50000Nm 3 / h flue gas, CO 2The concentration is 12-15vol%, the operating pressure is normal pressure, and the absorption temperature is 40-45℃. The energy-saving indicators of the system include: the total heat transfer coefficient is 2200W / (m 2 ·K), the heat recovery rate of the heat exchange network is 93%, and the regeneration energy consumption is 2.5GJ / tCO 2 , the temperature difference of the lean and rich liquid heat exchanger 4 is 8°C, and the temperature gradient of the regeneration tower 5 is 6.5°C / m. The overall reaction heat and energy consumption are lower.

[0059] Furthermore, in order to better prove that the present application uses the above-mentioned two-component secondary amine solution as the absorbent, and that the energy consumption of the entire system is lower than that of other existing absorbents, the following experimental comparison is carried out.

[0060] TMPDA+DETA, EIPA+DETN, TMPDA+TZ, TMPDA+MPD, TMPDA+MEA, TMPDA+BDA, TMPDA+AEEA were used as absorbents, respectively, where TMPDA is the abbreviation of tetramethylpropylenediamine (N,N,N',N'-Tetramethyl-1,3-propanediamine), DETA is the abbreviation of diethylenetriamine, TZ is the abbreviation of tetrazine, MPD is the abbreviation of metaphenylenediamine, MEA is the abbreviation of ethanolamine, BDA is the abbreviation of 1,4-butanediamine, and AEEA is the abbreviation of hydroxyethylethylenediamine. The above absorbents were used to test the regeneration degree under the water bath condition of 120 degrees Celsius within 1 minute, and the regeneration efficiency of each was calculated, such as Figure 2 It can be seen that at the same temperature, when the absorbent is EIPA+DETN, the regeneration efficiency is the highest.

[0061] In summary, the entire system uses DETN / EIPA two-component secondary amine as the absorbent, and the reaction heat is significantly reduced through the synergistic effect of DETN's low reaction heat characteristics and EIPA's steric effect; an innovative three-stage heat exchange network is designed, including an efficient lean-rich liquid heat exchanger 4, heat exchange between regenerated gas and rich liquid, and heat exchange between flue gas and rich liquid in absorption tower 1; regeneration tower 5 adopts a segmented heating method to achieve energy cascade utilization; an intelligent heat control system is equipped to ensure the coordinated and optimized operation of each heat exchange unit. The system uses a two-component secondary amine absorbent with low reaction heat to reduce the reaction heat, and combined with an efficient three-stage heat exchange network design, it can effectively reduce energy consumption; the total heat transfer coefficient of the system is not less than 2000W / (m 2 ·K), the heat recovery rate of the heat exchange network is over 90%, and the regeneration energy consumption is less than 2.5GJ / tCO 2 , which has significant energy-saving effect.

[0062] The above are only exemplary embodiments of the present invention and are not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A flue gas carbon dioxide capture and regeneration system based on a two-component secondary amine, characterized in that: It includes an absorption tower, a separator, a mixing tank, a lean and rich liquid heat exchanger and a regeneration mechanism; The flue gas inlet and rich liquid outlet of the absorption tower are respectively used to connect the CO2 gas source pipeline and the inlet of the separator, the upper lean liquid outlet and the lower rich liquid outlet of the separator are respectively used to connect the first inlet of the mixing tank and the first inlet of the lean-rich liquid heat exchanger, the first outlet of the lean-rich liquid heat exchanger is used to transport the rich liquid after heat exchange to the regeneration mechanism, the regenerated lean liquid outlet of the regeneration mechanism is used to connect the second inlet of the lean-rich liquid heat exchanger, the second outlet of the lean-rich liquid heat exchanger is used to connect the second inlet of the mixing tank, and the outlet of the mixing tank is used to transport the mixed lean liquid to the absorption tower; wherein the absorption tower is pre-installed with an absorbent, and the absorbent is a two-component secondary amine solution composed of diethylamine, N-ethylisopropylamine and water.

2. The flue gas carbon dioxide capture and regeneration system based on two-component secondary amine according to claim 1, characterized in that: The mass ratio of the diethylamine to the N-ethylisopropylamine is (60-70):(20-30), and the total amine concentration of the two-component secondary amine solution is 1-2 mol / L.

3. The flue gas carbon dioxide capture and regeneration system based on two-component secondary amine according to claim 1, characterized in that: The regeneration mechanism includes a regeneration tower and a reboiler, the reboiler is connected to the bottom of the regeneration tower, the first outlet of the lean-rich liquid heat exchanger is connected to the corresponding inlet of the reboiler through a corresponding pipeline, the reflux port of the reboiler is connected to the lower part of the regeneration tower through a corresponding pipeline, the bottom of the regeneration tower is also connected to the reboiler through a corresponding pipeline, and the regenerated lean liquid outlet is arranged at the bottom of the reboiler.

4. The flue gas carbon dioxide capture and regeneration system based on two-component secondary amine according to claim 3, characterized in that: The absorption tower and the regeneration tower are both packed tower structures, wherein a plurality of packing layers spaced apart from each other are provided in the packed tower structure, and the packing layers are corrugated metal perforated plates.

5. The flue gas carbon dioxide capture and regeneration system based on two-component secondary amine according to claim 3, characterized in that: The flue gas carbon dioxide capture and regeneration device based on two-component secondary amine also includes a regeneration gas cooler. The regeneration gas outlet at the top of the regeneration tower is used to connect to the inlet of the regeneration gas cooler. The condensate outlet of the regeneration gas cooler is used to reflux the condensate into the regeneration tower. The gas outlet of the regeneration gas cooler is used to connect to the CO2 emission pipeline.

6. The flue gas carbon dioxide capture and regeneration system based on two-component secondary amine according to claim 5, characterized in that: A first heat exchanger is also provided on the rich liquid pipeline between the lower rich liquid outlet of the separator and the first inlet of the lean-rich liquid heat exchanger, which is used to exchange heat between the regenerated gas at the regenerated gas outlet at the top of the regeneration tower and the upper rich liquid in the rich liquid pipeline. The regenerated gas after heat exchange is then transported to the regenerated gas cooler.

7. The flue gas carbon dioxide capture and regeneration system based on two-component secondary amine according to claim 6, characterized in that: The flue gas carbon dioxide capture and regeneration device based on two-component secondary amine also includes a water scrubber, the flue gas outlet at the top of the absorption tower is used to connect to the flue gas inlet of the water scrubber, the water washing liquid outlet of the water scrubber is used to reflux the water washing liquid into the absorption tower, and the flue gas discharge port of the water scrubber is used to connect to the decarbonization flue gas discharge pipeline.

8. The flue gas carbon dioxide capture and regeneration system based on two-component secondary amine according to claim 7, characterized in that: A second heat exchanger is also provided on the rich liquid pipeline for exchanging heat between the flue gas at the flue gas outlet at the top of the absorption tower and the upper rich liquid in the rich liquid pipeline. The flue gas after heat exchange is then transported to the water washing tower.

9. The flue gas carbon dioxide capture and regeneration system based on two-component secondary amine according to claim 1, characterized in that: The mixing tank is also connected to a replenishing liquid pipeline for replenishing N-ethylisopropylamine; A lean liquid cooler is also provided on the pipeline between the outlet of the mixing tank and the absorbent inlet of the absorption tower.

10. The flue gas carbon dioxide capture and regeneration system based on two-component secondary amine according to claim 1, characterized in that: The mixing tank comprises a metal tank body, the outer side of the metal tank body is wrapped with a heat-insulating material layer, an agitator is arranged in the metal tank body, and a plurality of guide plates are circumferentially arranged at intervals on the inner wall of the metal tank body.

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