Compact ship tail gas carbon dioxide trapping system and trapping method

Abstract

The invention relates to a compact ship tail gas carbon dioxide capture system and method, and the compact ship tail gas carbon dioxide capture system comprises a flue gas pretreatment unit, a hollow fiber membrane reactor absorption unit, a flue gas heat exchange unit, a multi-stage flash evaporation desorption unit, a CO2 compression liquefaction unit and a CO2 storage lightering unit. The compact ship tail gas carbon dioxide capture system has the advantages that the occupied area of the system is reduced, the operation cost of the system is reduced, and efficient capture of ship tail gas CO2 is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of ships, and in particular relates to a compact ship exhaust carbon dioxide capture system and a capture method. Background Art

[0002] Greenhouse gases such as CO2 emitted during the use of fossil fuels lead to global warming, causing frequent extreme weather events such as melting glaciers, droughts and waterlogging, desertification, increased pests and diseases, and other hazards. The shipping industry is an important support for global trade and world economic development, and is also the most economical and energy-saving mode of transportation. However, atmospheric pollutants including greenhouse gases generated by the combustion of fuels that power ships are emitted into the atmosphere, which will have a negative impact on the environment.

[0003] In order to reduce greenhouse gas emissions, the shipping industry has also introduced a series of emission reduction policies. Ship exhaust CO2 capture technology is to separate and purify the CO2 generated by the ship from the exhaust gas through physical or chemical means, and then compress and liquefy it for storage. After docking, the CO2 is transferred to land and utilized or sealed to avoid CO2 emissions into the atmosphere and achieve ship decarbonization. At present, the main methods for capturing CO2 from flue gas include absorption, adsorption, membrane separation and low-temperature separation. Among them, the amine chemical absorption method is currently the most respected ship exhaust CO2 capture method. Although the amine chemical absorption method has the advantages of fast CO2 absorption rate, large load capacity, renewable absorption liquid, high purity of captured CO2, and high technical maturity, the equipment used also has the disadvantages of large size, high energy consumption, and traditional devices such as packed towers are prone to channel flow, liquid flooding, and mist entrainment.

[0004] Since the installation space and steam supply of ships are limited, it is urgent to develop a compact ship exhaust CO2 capture system in combination with ship installation conditions to address the problems of large size and high energy consumption of traditional amine chemical absorption equipment. Summary of the invention

[0005] In view of the shortcomings in the relevant technologies, the present invention provides a compact ship exhaust carbon dioxide capture system and capture method to reduce the system footprint and system operating costs, achieve efficient capture of ship exhaust CO2, meet the requirements of the shipping industry to achieve net zero emissions, and solve the technical problems of large equipment size and high energy consumption of traditional alcohol amine chemical absorption method.

[0006] In one aspect, the present invention provides a compact ship exhaust carbon dioxide capture system, comprising:

[0007] A flue gas pretreatment unit, the flue gas pretreatment unit includes a flue gas pretreatment tower, and the flue gas pretreatment tower is used to pretreat the flue gas;

[0008] The hollow fiber membrane reactor absorption unit is connected to the flue gas pretreatment tower. The hollow fiber membrane reactor absorption unit includes a hollow fiber membrane reactor. The hollow fiber membrane reactor is connected to the flue gas pretreatment tower. The flue gas pretreated by the flue gas pretreatment tower is pressurized and enters the hollow fiber membrane reactor to contact with the alcohol amine absorbent in the hollow fiber membrane reactor to remove CO2 in the flue gas.

[0009] The flue gas heat exchange unit is connected to the flue gas pretreatment tower and the hollow fiber membrane reactor respectively. The alcohol amine rich liquid that has absorbed CO2 after being treated by the hollow fiber membrane reactor is heated by the high-temperature flue gas from the ship engine in the flue gas heat exchange unit. The cooled flue gas enters the flue gas pretreatment tower for pretreatment.

[0010] The multi-stage flash desorption unit is connected to the flue gas heat exchange unit. The alcohol amine rich liquid that has absorbed CO2 after being heated by the flue gas heat exchange unit is adiabatically flashed in the multi-stage flash desorption unit. The CO2 loaded in the alcohol amine rich liquid is removed step by step. The alcohol amine lean liquid from which CO2 has been removed is cooled by the flue gas heat exchange unit and then refluxed to the hollow fiber membrane reactor for circulation.

[0011] The CO2 compression and liquefaction unit is connected to the hollow fiber membrane reactor and the multi-stage flash desorption unit respectively. The CO2 gas obtained after being treated by the multi-stage flash desorption unit and the separated fresh water after cooling enter the hollow fiber membrane reactor. The CO2 gas is compressed and liquefied in the CO2 compression and liquefaction unit;

[0012] The CO2 storage and transfer unit is connected to the CO2 compression and liquefaction unit. The CO2 storage and transfer unit includes a CO2 storage tank connected to the CO2 compression and liquefaction unit and a CO2 transfer unit connected to the CO2 storage tank. The liquid CO2 treated by the CO2 compression and liquefaction unit is stored in the CO2 storage tank and transported to the shore for processing by the CO2 transfer unit.

[0013] In some embodiments, the flue gas pretreatment unit further includes

[0014] a seawater pump connected to the first inlet of the flue gas pretreatment tower;

[0015] A seawater supply valve is provided between the flue gas pretreatment tower and the seawater pump;

[0016] A first water quality detector is arranged between the seawater pump and the seawater supply valve;

[0017] A second flue gas supply valve is arranged at the second inlet of the flue gas pretreatment tower;

[0018] A third flue gas supply valve is arranged at the first outlet of the flue gas pretreatment tower;

[0019] The second water quality detector is arranged at the second outlet of the flue gas pretreatment tower.

[0020] In some of the embodiments, the bottom inlet of the hollow fiber membrane reactor is connected to the first outlet of the flue gas pretreatment tower, and the hollow fiber membrane reactor includes a shell, a plurality of hollow fiber membranes arranged in the shell, and a metal screen arranged at both ends of the hollow fiber membranes, and the inner diameter of the metal screen is larger than the outer diameter of the hollow fiber membrane.

[0021] In some of the embodiments, the hollow fiber membrane is made of polypropylene, polyvinylidene fluoride or polytetrafluoroethylene, with an average pore size of 0.01-0.1 μm and a porosity greater than 50%.

[0022] In some embodiments, the flue gas heat exchange unit includes

[0023] A rich liquid pump, wherein the inlet of the rich liquid pump is connected to the hollow fiber membrane reactor;

[0024] A lean-rich liquid heat exchanger, wherein a first inlet of the lean-rich liquid heat exchanger is connected to an outlet of a rich liquid pump;

[0025] A lean liquid cooler, wherein the lean liquid cooler inlet is connected to the first outlet of the lean-rich liquid heat exchanger, and the lean liquid cooler outlet is connected to the hollow fiber membrane reactor;

[0026] A lean liquid pump, wherein the outlet of the lean liquid pump is connected to the second inlet of the lean and rich liquid heat exchanger;

[0027] A flue gas heat exchanger, wherein the first inlet of the flue gas heat exchanger is connected to the ship engine, the second inlet of the flue gas heat exchanger is connected to the second outlet of the lean-rich liquid heat exchanger, and the first outlet of the flue gas heat exchanger is connected to the second inlet of the flue gas pretreatment tower;

[0028] The first flue gas supply valve is arranged between the flue gas heat exchanger and the ship engine.

[0029] In some of the embodiments, the multi-stage flash desorption unit includes a primary flash tank, a secondary flash tank and a tertiary flash tank connected in sequence, wherein the inlet of the primary flash tank is connected to the second outlet of the flue gas heat exchanger, the bottom outlet of the primary flash tank is connected to the inlet of the secondary flash tank, the bottom outlet of the secondary flash tank is connected to the inlet of the tertiary flash tank, and the bottom outlet of the tertiary flash tank is connected to the inlet of the lean liquid pump.

[0030] In some embodiments, the CO2 compression and liquefaction unit includes

[0031] A multi-stage CO2 compressor, wherein a first inlet of the multi-stage CO2 compressor is connected to an upper outlet of a first-stage flash tank, a second inlet of the multi-stage CO2 compressor is connected to an upper outlet of a second-stage flash tank, and a third inlet of the multi-stage CO2 compressor is connected to an upper outlet of a third-stage flash tank;

[0032] A CO2 cooler, wherein the inlet of the CO2 cooler is connected to the outlet of a multi-stage CO2 compressor;

[0033] Gas-liquid separation tank, the inlet of the gas-liquid separation tank is connected to the outlet of the CO2 cooler, and a liquid level sensor is provided on the gas-liquid separation tank;

[0034] A fresh water pump, wherein the fresh water pump inlet is connected to the first outlet of the gas-liquid separation tank, and the fresh water pump outlet is connected to the hollow fiber membrane reactor;

[0035] A fresh water regulating valve is arranged between the fresh water pump and the hollow fiber membrane reactor;

[0036] A CO2 compression and liquefaction device, wherein the first inlet of the CO2 compression and liquefaction device is connected to the second outlet of the gas-liquid separation tank, the second inlet of the CO2 compression and liquefaction device is connected to the first outlet of the CO2 storage tank, and the outlet of the CO2 compression and liquefaction device is connected to the inlet of the CO2 storage tank.

[0037] In some embodiments, the CO2 storage and transfer unit further includes

[0038] A pressure sensor is installed on the CO2 storage tank;

[0039] A gaseous CO2 reflux regulating valve is arranged between the second inlet of the CO2 compression and liquefaction device and the first outlet of the CO2 storage tank;

[0040] A liquid CO2 supply pump connected to the second outlet of the CO2 storage tank;

[0041] A first liquid CO2 supply valve is arranged at the inlet of the CO2 storage tank;

[0042] The second liquid CO2 supply valve is arranged between the CO2 transfer unit and the liquid CO2 supply pump.

[0043] Another aspect of the present invention further provides a capture method for the above-mentioned compact ship exhaust carbon dioxide capture system, comprising the following steps:

[0044] The high-temperature flue gas from the ship engine passes through the flue gas heat exchange unit to heat the alcohol amine rich liquid, and then enters the flue gas pretreatment tower, where it comes into contact with the seawater entering the flue gas pretreatment tower to cool down, remove dust and desulfurize.

[0045] The flue gas treated in the flue gas pretreatment tower is pressurized and then enters the hollow fiber membrane reactor, where it contacts with the alcohol amine absorbent in the hollow fiber membrane reactor to remove CO2 from the flue gas;

[0046] The alcohol amine rich liquid that has absorbed CO2 enters the flue gas heat exchange unit for heating and then enters the multi-stage flash desorption unit for adiabatic flash evaporation to remove CO2 step by step;

[0047] The CO2 gas removed by the multi-stage flash desorption unit enters the CO2 compression and liquefaction unit for compression and liquefaction, and the liquid CO2 is transported to the CO2 storage tank for storage. When the ship docks at the port, the liquid CO2 is transported to the CO2 transfer unit, and then transported to the shore for treatment.

[0048] In some of the embodiments, the amine lean liquid from which CO2 is removed by a multi-stage flash desorption unit is cooled by a flue gas heat exchange unit and then refluxed to the hollow fiber membrane reactor for circulation.

[0049] Based on the above technical scheme, the compact ship exhaust carbon dioxide capture system of the embodiment of the present invention can achieve substantial savings in ship installation space, reduce equipment investment costs and operating costs, and be green and environmentally friendly; the present invention adopts a hollow fiber membrane reactor for CO2 absorption, and has the advantages of high CO2 selectivity, small footprint and low investment cost; the present invention adopts a three-stage flash tank for CO2 desorption, which can not only reduce equipment investment costs, but also reduce the CO2 precipitation temperature during the flash process, reduce the cooling load, and achieve the purpose of saving operating costs; the present invention uses a flue gas heat exchanger to provide heat for the CO2 desorption unit, thereby realizing the utilization of ship waste heat, without the need to supply steam to the system, and significantly improving the overall energy efficiency of the system through the recovery of waste heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0051] Figure 1 It is a schematic structural diagram of a compact ship exhaust carbon dioxide capture system according to the present invention;

[0052] Figure 2 It is a schematic structural diagram of a hollow fiber membrane reactor of a compact ship exhaust carbon dioxide capture system of the present invention;

[0053] In the figure:

[0054] 100. Flue gas pretreatment unit, 110. Flue gas pretreatment tower, 111. First inlet of flue gas pretreatment tower, 112. Second inlet of flue gas pretreatment tower, 113. First outlet of flue gas pretreatment tower, 114. Second outlet of flue gas pretreatment tower, 120. Second flue gas supply valve, 130. Seawater pump, 140. Seawater supply valve, 150. First water quality detector, 160. Second water quality detector, 170. Third flue gas supply valve, 180. Fan;

[0055] 200. hollow fiber membrane reactor absorption unit, 210. hollow fiber membrane reactor, 211. shell, 212. hollow fiber membrane, 213. metal screen, 220. gas analyzer;

[0056] 300, flue gas heat exchange unit, 310, rich liquid pump, 320, lean and rich liquid heat exchanger, 321, first inlet of lean and rich liquid heat exchanger, 322, second inlet of lean and rich liquid heat exchanger, 323, first outlet of lean and rich liquid heat exchanger, 324, second outlet of lean and rich liquid heat exchanger, 330, lean liquid pump, 340, flue gas heat exchanger, 341, first inlet of flue gas heat exchanger, 342, second inlet of flue gas heat exchanger, 343, first outlet of flue gas heat exchanger, 344, second outlet of flue gas heat exchanger, 350, lean liquid cooler, 360, first flue gas supply valve;

[0057] 400, multi-stage flash desorption unit, 410, primary flash tank, 420, secondary flash tank, 430, tertiary flash tank;

[0058] 500, CO2 compression and liquefaction unit, 510, multi-stage CO2 compressor, 511, first inlet of multi-stage CO2 compressor, 512, second inlet of multi-stage CO2 compressor, 513, third inlet of multi-stage CO2 compressor, 520, CO2 cooler, 530, gas-liquid separation tank, 531, liquid level sensor, 532, first outlet of gas-liquid separation tank, 533, second outlet of gas-liquid separation tank, 540, CO2 compression and liquefaction device, 541, first inlet of CO2 compression and liquefaction device, 542, second inlet of CO2 compression and liquefaction device, 550, fresh water pump, 560, fresh water regulating valve;

[0059] 600, CO2 storage and transfer unit, 610, first liquid CO2 supply valve, 620, CO2 storage tank, 621, first outlet of CO2 storage tank, 622, second outlet of CO2 storage tank, 623, pressure sensor, 630, gaseous CO2 reflux regulating valve, 640, liquid CO2 supply pump, 650, second liquid CO2 supply valve, 660, CO2 transfer unit;

[0060] 710. Ship engine. 720. Smoke exhaust valve. DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0062] The embodiments of the present invention provide a compact ship exhaust carbon dioxide capture system and capture method for ships equipped with diesel / LNG / methanol fuel engines, which have limited installation space and limited steam supply. The system can significantly save ship installation space and reduce equipment investment costs. By using ship exhaust gas to provide heat for the CO2 desorption unit, the overall operating cost of the system can be significantly reduced, which is green and environmentally friendly.

[0063] As attached Figure 1 As shown, in an exemplary embodiment of a compact ship exhaust carbon dioxide capture system of the present invention, the compact ship exhaust carbon dioxide capture system includes a flue gas pretreatment unit 100, a hollow fiber membrane reactor absorption unit 200, a flue gas heat exchange unit 300, a multi-stage flash desorption unit 400, a CO2 compression liquefaction unit 500 and a CO2 storage and transportation unit 600.

[0064] In the above exemplary embodiment, the flue gas pretreatment unit 100 can realize the cooling, dust removal and desulfurization of flue gas. The flue gas pretreatment unit 100 includes a flue gas pretreatment tower 110; a seawater pump 130, connected to the first inlet 111 of the flue gas pretreatment tower; a seawater supply valve 140, arranged between the flue gas pretreatment tower 110 and the seawater pump 130; a first water quality detector 150, arranged between the seawater pump 130 and the seawater supply valve 140, which can detect the pH value, PAH value and turbidity of seawater; a second flue gas supply valve 120, arranged at the second inlet 112 of the flue gas pretreatment tower; a third flue gas supply valve 170, arranged at the first outlet 113 of the flue gas pretreatment tower; and a second water quality detector 160, arranged at the second outlet 114 of the flue gas pretreatment tower. The second outlet 114 of the flue gas pretreatment tower is a wastewater discharge outlet. The second water quality detector 160 arranged at the second outlet 114 of the flue gas pretreatment tower can detect the pH value, PAH value and turbidity of the wastewater.

[0065] Seawater from the sea area where the ship is sailing is extracted by a seawater pump 130, and sprayed into the flue gas pretreatment tower 110 after passing through a seawater supply valve 140; when the ship exhaust carbon dioxide capture system is turned on, the high-temperature flue gas from the ship engine is cooled down after passing through a flue gas heat exchanger 340, and then enters the flue gas pretreatment tower 110 through a second flue gas supply valve 120; the seawater contacts the flue gas in the flue gas pretreatment tower 110, removes ash from the flue gas, reduces the flue gas temperature to about 40°C, and reduces the SO2 concentration in the flue gas to below 20ppm, thereby achieving the purpose of cooling, dust removal and desulfurization, and the wastewater after washing the flue gas is discharged outside the ship through the wastewater outlet.

[0066] In the above exemplary embodiment, the hollow fiber membrane reactor absorption unit 200 is connected to the flue gas pretreatment tower 110, which can achieve high CO2 selectivity, compact structure and low investment cost. The hollow fiber membrane reactor absorption unit 200 includes a hollow fiber membrane reactor 210, the bottom inlet of the hollow fiber membrane reactor 210 is connected to the first outlet 113 of the flue gas pretreatment tower. Compared with the packed tower, the hollow fiber membrane reactor 210 can provide up to 3000m 2 / m 3 The specific surface area per unit volume has increased by dozens of times. Therefore, compared with the packed tower, the volume of the hollow fiber membrane reactor can be reduced by dozens of times, greatly reducing the installation area. Figure 2 As shown, the hollow fiber membrane reactor 210 is composed of a shell 211, a hollow fiber membrane 212 and a metal screen 213. Among them, the hollow fiber membrane 212 is made of polypropylene, polyvinylidene fluoride or polytetrafluoroethylene, with an average pore size of 0.01-0.1 μm and a porosity of more than 50%. The number of hollow fiber membranes 212 is determined by the flow rate of the alcohol amine solution. Since the hollow fiber membrane itself is non-rigid, the membrane filaments are easily twisted and entangled during the assembly process, forming a "dead zone" and affecting the mass transfer process. In order to avoid the above problem, a metal screen 213 with a size slightly larger than the outer diameter of the membrane filament is added to both ends of the membrane assembly, and the mesh holes at the corresponding ends allow the membrane filaments to pass through in sequence.

[0067] After being processed by the flue gas pretreatment unit 100, the flue gas after cooling, dust removal and desulfurization passes through the third flue gas supply valve 170 and is pressurized by the fan to obtain flue gas with a temperature of 40°C and a pressure of 5kpa, which enters the hollow fiber membrane reactor 210. The alcohol amine absorbent and the flue gas flow in opposite directions on both sides of the hydrophobic membrane without contacting each other, wherein the alcohol amine absorbent flows through the tube side and the flue gas flows through the shell side; under the action of the concentration gradient, the CO2 gas in the flue gas penetrates and diffuses through the membrane pores to the gas-liquid contact surface, and is then absorbed by the alcohol amine absorbent, thereby realizing the separation of the CO2 gas in the flue gas; wherein, the flue gas from which CO2 is removed is discharged into the atmosphere through the upper part of the hollow fiber membrane reactor 210, and the gas analyzer 220 arranged above the hollow fiber membrane reactor 210 can analyze the CO2 concentration in the outlet flue gas for calculating the CO2 removal efficiency.

[0068] In the above exemplary embodiment, the flue gas heat exchange unit 300 is connected to the flue gas pretreatment tower 110 and the hollow fiber membrane reactor 210 respectively, and can provide heat for the CO2 desorption unit for heating the alcohol amine solution to realize the utilization of waste heat from the ship. The flue gas heat exchange unit 300 includes a rich liquid pump 310, the inlet of the rich liquid pump 310 is connected to the hollow fiber membrane reactor 210; a lean and rich liquid heat exchanger 320, the first inlet 321 of the lean and rich liquid heat exchanger is connected to the outlet of the rich liquid pump 310; a lean liquid cooler 350, the inlet of the lean liquid cooler 350 is connected to the first outlet 323 of the lean and rich liquid heat exchanger, and the outlet of the lean liquid cooler 350 is connected to the hollow fiber membrane reactor 210; a lean liquid pump 330, the outlet of the lean liquid pump 330 is connected to the second inlet 324 of the lean and rich liquid heat exchanger; a flue gas heat exchanger 340, the first inlet 341 of the flue gas heat exchanger is connected to the ship engine 710, the second inlet 342 of the flue gas heat exchanger is connected to the second outlet 324 of the lean and rich liquid heat exchanger, and the first outlet 343 of the flue gas heat exchanger is connected to the second inlet 112 of the flue gas pretreatment tower; a first flue gas supply valve 360 ​​is arranged between the flue gas heat exchanger 340 and the ship engine 710.

[0069] The alcoholamine rich liquid that has absorbed CO2 is pressurized by the rich liquid pump 310 and sent to the lean-rich liquid heat exchanger 320 to exchange heat with the high-temperature alcoholamine lean liquid. The alcoholamine rich liquid after preliminary heating enters the flue gas heat exchanger 340 for further heating to 120-130°C. In the ship exhaust carbon dioxide capture system start-up mode, the first flue gas supply valve 360 ​​is opened, and the flue gas discharge valve 720 connected to the ship engine 710 is closed. The high-temperature flue gas from the ship engine 710 first passes through the flue gas heat exchanger 340 to heat the alcoholamine rich liquid. The temperature of the heated alcoholamine rich liquid reaches 120-130°C, and the flue gas temperature drops to about 100°C. The cooled flue gas passes through the second flue gas supply valve 120 and enters the flue gas pretreatment tower 110 for cooling, dust removal and desulfurization. The heated alcoholamine rich liquid enters the multi-stage flash desorption unit 400 for adiabatic flash evaporation.

[0070] In the above exemplary embodiment, the multi-stage flash desorption unit 400 is connected to the flue gas heat exchange unit 300, which can realize CO2 desorption, not only reducing the equipment investment cost, but also reducing the CO2 precipitation temperature during the flash process, reducing the cooling load, and achieving the purpose of saving operating costs. The multi-stage flash desorption unit 400 includes a primary flash tank 410, a secondary flash tank 420, and a tertiary flash tank 430 connected in sequence, wherein the inlet of the primary flash tank 410 is connected to the second outlet 344 of the flue gas heat exchanger, the bottom outlet of the primary flash tank 410 is connected to the inlet of the secondary flash tank 420, the bottom outlet of the secondary flash tank 420 is connected to the inlet of the tertiary flash tank 430, and the bottom outlet of the tertiary flash tank 430 is connected to the inlet of the lean liquid pump 330. The alcoholamine solution heated by the flue gas heat exchanger 340 is sequentially subjected to adiabatic flash evaporation in the primary flash tank 410, the secondary flash tank 420 and the tertiary flash tank 430, and the CO2 loaded in the alcoholamine rich liquid is removed step by step. The CO2 gas obtained in each stage enters the multi-stage CO2 compressor 510 of the CO2 compression liquefaction unit 500 for compression. The temperature of the alcoholamine lean liquid after CO2 removal is still as high as 100-110°C. After being pressurized by the lean liquid pump 330, it is sent to the lean-rich liquid heat exchanger 320 to provide heat for the alcoholamine rich liquid, and then further cooled to 40°C by the lean liquid cooler 350 and sent to the hollow fiber membrane reactor 210 to react with the CO2 in the flue gas, so as to achieve the purpose of cyclic removal of CO2.

[0071] In the above exemplary embodiment, the CO2 compression and liquefaction unit 500 is respectively connected to the hollow fiber membrane reactor 210 and the multi-stage flash desorption unit 400, so as to realize CO2 compression and liquefaction. The CO2 compression and liquefaction unit 500 includes a multi-stage CO2 compressor 510, wherein the first inlet 511 of the multi-stage CO2 compressor is connected to the upper outlet of the first flash tank 410, the second inlet 512 of the multi-stage CO2 compressor is connected to the upper outlet of the second flash tank 420, and the third inlet 513 of the multi-stage CO2 compressor is connected to the upper outlet of the third flash tank 430; a CO2 cooler 520, wherein the inlet of the CO2 cooler 520 is connected to the outlet of the multi-stage CO2 compressor 510; and a gas-liquid separation tank 530, wherein the inlet of the gas-liquid separation tank 530 is connected to the outlet of the CO2 cooler 520, and a gas-liquid separation tank 530 is provided on the gas-liquid separation tank 530. A liquid level sensor 531; a fresh water pump 550, wherein the inlet of the fresh water pump 550 is connected to the first outlet 532 of the gas-liquid separation tank, and the outlet of the fresh water pump 550 is connected to the hollow fiber membrane reactor 210; a fresh water regulating valve 560, which is arranged between the fresh water pump 550 and the hollow fiber membrane reactor 210; a CO2 compression and liquefaction device 540, wherein the first inlet 541 of the CO2 compression and liquefaction device is connected to the second outlet 533 of the gas-liquid separation tank, the second inlet 542 of the CO2 compression and liquefaction device is connected to the first outlet 621 of the CO2 storage tank, and the outlet of the CO2 compression and liquefaction device 540 is connected to the inlet of the CO2 storage tank 620.

[0072] The alcohol amine rich liquid that has absorbed CO2 is adiabatically flashed by a three-stage flash tank after pressurization and heat exchange. The CO2 loaded in the alcohol amine rich liquid is removed step by step and enters the multi-stage CO2 compressor 510 for compression. The compressed CO2 gas is cooled by the CO2 cooler and enters the gas-liquid separation tank 530 to separate the water in CO2. The CO2 gas at the outlet of the gas-liquid separation tank 530 is pressurized to 14 bar by the CO2 compression liquefaction device 540 and cooled to -30°C for liquefaction. The fresh water separated from the gas-liquid separation tank 530 is pressurized by the fresh water pump 550 and transported to the hollow fiber membrane reactor 210 to ensure the water balance of the system. The opening of the fresh water regulating valve 560 is controlled by the liquid level sensor 531. When the liquid level of the gas-liquid separation tank 530 is too high, the opening of the fresh water regulating valve 560 is increased to prevent fresh water from overflowing from the top of the gas-liquid separation tank 530.

[0073] In the above exemplary embodiment, the CO2 storage and transportation unit 600 is connected to the CO2 compression and liquefaction unit 500, and can realize temporary storage and transportation of CO2 to the shore. The CO2 storage and transportation unit 600 includes a CO2 storage tank 620, which is connected to the CO2 compression and liquefaction device 540; a CO2 transportation unit 660, which is connected to the CO2 storage tank 620; a pressure sensor 623, which is arranged on the CO2 storage tank 620, and is used to display the pressure of the CO2 storage tank 620; a gaseous CO2 reflux regulating valve 630, which is arranged between the second inlet 542 of the CO2 compression and liquefaction device and the first outlet 621 of the CO2 storage tank; a liquid CO2 supply pump 640, which is connected to the second outlet 622 of the CO2 storage tank; a first liquid CO2 supply valve 610, which is arranged at the inlet of the CO2 storage tank 620; and a second liquid CO2 supply valve 650, which is arranged between the CO2 transportation unit 660 and the liquid CO2 supply pump 640. The liquid CO2 liquefied by the CO2 compression and liquefaction device 540 is transported to the CO2 storage tank 620 for storage via the first liquid CO2 supply valve 610. When the pressure sensor 623 shows that the pressure of the CO2 storage tank 620 is too high, the opening of the gaseous CO2 reflux regulating valve 630 increases, and the gaseous CO2 flows back to the CO2 compression and liquefaction device 540 for liquefaction treatment, thereby reducing the pressure of the CO2 storage tank 620. When the ship docks at the port, the liquid CO2 is transported to the CO2 transfer unit 660 via the liquid CO2 supply pump 640 and the second liquid CO2 supply valve 650, and then transported to the shore for treatment by the CO2 transfer unit 660.

[0074] The capture method of the compact ship exhaust carbon dioxide capture system of the present invention comprises the following steps:

[0075] The high-temperature flue gas from the ship engine 710 passes through the flue gas heat exchange unit 300 to heat the alcohol amine rich liquid, and then enters the flue gas pretreatment tower 110, where it comes into contact with the seawater entering the flue gas pretreatment tower 110 to cool down, remove dust and desulfurize.

[0076] The flue gas treated by the flue gas pretreatment tower 110 is pressurized and enters the hollow fiber membrane reactor 210, and contacts with the alcohol amine absorbent in the hollow fiber membrane reactor 210 to remove CO2 in the flue gas;

[0077] The alcohol amine rich liquid that has absorbed CO2 enters the flue gas heat exchange unit 300 for heating and then enters the multi-stage flash desorption unit 400 for adiabatic flash evaporation to remove CO2 step by step. The alcohol amine lean liquid from which CO2 has been removed by the multi-stage flash desorption unit 400 is cooled by the flue gas heat exchange unit 300 and then refluxed to the hollow fiber membrane reactor 210 for circulation.

[0078] The CO2 gas removed by the multi-stage flash desorption unit 400 enters the CO2 compression and liquefaction unit 500 for compression and liquefaction, and the liquid CO2 is transported to the CO2 storage tank 620 for storage. When the ship docks at the port, the liquid CO2 is transported to the CO2 transfer unit 660, and then transported to the shore for processing.

[0079] The following is combined with Figure 1 The specific working process of an embodiment of the compact ship exhaust carbon dioxide capture system of the present invention is described as follows:

[0080] In the ship exhaust CO2 capture system start-up mode, the first flue gas supply valve 360 ​​is opened, the flue gas discharge valve 720 is closed, and the high-temperature flue gas from the ship engine 710 first passes through the flue gas heat exchanger 340 to heat the alcohol amine rich liquid. The temperature of the heated alcohol amine rich liquid reaches 120-130°C, and the flue gas temperature drops to about 100°C. The cooled flue gas passes through the second flue gas supply valve 120 and enters the flue gas pretreatment tower 110; seawater from the ship's sailing area is extracted by the seawater pump 130, and is sprayed into the flue gas pretreatment tower 110 after passing through the seawater supply valve 140; the seawater contacts the flue gas in the flue gas pretreatment tower 110, removes the ash in the flue gas, reduces the flue gas temperature to about 40°C, and reduces the SO2 concentration in the flue gas to below 20ppm, thereby achieving the purpose of cooling, dust removal and desulfurization of the flue gas, and the wastewater after washing the flue gas is discharged to the outside of the ship through the wastewater outlet.

[0081] After cooling, dust removal and desulfurization, the flue gas passes through the third flue gas supply valve 170, is pressurized to 5kPa by the fan 180, and enters the hollow fiber membrane reactor 210; the alcohol amine absorbent and the flue gas flow in opposite directions on both sides of the hydrophobic membrane of the hollow fiber membrane reactor 210 without contacting each other, wherein the alcohol amine absorbent flows through the tube side and the flue gas flows through the shell side; under the action of the concentration gradient, the CO2 gas in the flue gas penetrates and diffuses through the membrane pores to the gas-liquid contact surface, and then is absorbed by the alcohol amine absorbent, thereby realizing the separation of the CO2 gas in the flue gas.

[0082] The flue gas from which CO2 is removed is discharged into the atmosphere through the upper part of the hollow fiber membrane reactor 210. The gas analyzer 220 can analyze the CO2 concentration in the outlet flue gas for calculating the CO2 removal efficiency. The rich alcoholamine liquid that has absorbed CO2 is pressurized by the rich liquid pump and sent to the lean-rich liquid heat exchanger 320 to exchange heat with the high-temperature lean alcoholamine liquid. The alcoholamine rich liquid after preliminary heating enters the flue gas heat exchanger 340 for further heating to 120-130°C, and then passes through the first-stage flash tank 410, the second-stage flash tank 420 and the third-stage flash tank 430 for adiabatic flash evaporation in turn, and the CO2 loaded in the alcoholamine rich liquid is removed step by step. The CO2 gas obtained in each stage enters the multi-stage CO2 compressor 510 for compression, and then enters the gas-liquid separation tank 530 after being cooled by the CO2 cooler 520 to achieve the separation of water in the CO2. Among them, the temperature of the alkanolamine lean liquid from which CO2 is removed is still as high as 100-110°C. After being pressurized by the lean liquid pump 330, it is sent to the lean-rich liquid heat exchanger 320 to provide heat for the alkanolamine rich liquid, and then further cooled to 40°C by the lean liquid cooler 350 and sent to the hollow fiber membrane reactor 210 to react with CO2 in the flue gas, thereby achieving the purpose of cyclic removal of CO2.

[0083] Fresh water separated from the gas-liquid separation tank 530 is pressurized by the fresh water pump 550 and then transported to the hollow fiber membrane reactor 210 to ensure the water balance of the system; the fresh water regulating valve 560 is opened by the liquid level sensor 531. When the liquid level of the gas-liquid separation tank 530 is too high, the fresh water regulating valve 560 is opened to prevent fresh water from overflowing from the top of the gas-liquid separation tank 530. The CO2 gas at the outlet of the gas-liquid separation tank 530 is pressurized to 14 bar by the CO2 compression and liquefaction unit 500 and cooled to -30°C for liquefaction; the liquid CO2 is sent to the CO2 storage tank 620 for storage through the first liquid CO2 supply valve 610. When the pressure sensor 623 shows that the pressure of the storage tank is too high, the opening of the gaseous CO2 reflux regulating valve 630 is increased, and the gaseous CO2 is refluxed to the CO2 compression and liquefaction device 540 for liquefaction treatment, thereby reducing the pressure of the CO2 storage tank 620. When the ship docks at the port, the liquid CO2 is transported to the CO2 transfer unit 660 via the liquid CO2 supply pump 640 and the second liquid CO2 supply valve 650, and then transported to the shore for processing by the CO2 transfer unit 660.

[0084] Through the description of the embodiments of the compact ship exhaust carbon dioxide capture system of the present invention, it can be seen that the compact ship exhaust carbon dioxide capture system of the present invention has the following advantages:

[0085] 1. Compared with the traditional chemical absorption method that uses a packed tower to absorb CO2, the packed tower has the problems of large floor space, high initial investment cost, easy channeling, flooding and mist entrainment, etc. The present invention uses a hollow fiber membrane reactor to replace the traditional packed tower for CO2 absorption, which has the advantages of high CO2 selectivity, compact structure and low investment cost;

[0086] 2. The present invention adopts a three-stage flash tank to replace the traditional packed tower for CO2 desorption, which can not only reduce the equipment investment cost, but also reduce the CO2 precipitation temperature during the flash evaporation process, reduce the cooling load, and achieve the purpose of saving operating costs;

[0087] 3. The present invention uses a flue gas heat exchanger instead of a traditional steam reboiler to provide heat for the CO2 desorption unit, thereby realizing the utilization of waste heat from the ship. There is no need to supply steam to the system, and the overall energy efficiency of the system is significantly improved by recovering waste heat.

[0088] Finally, it should be noted that: the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0089] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A compact ship exhaust carbon dioxide capture system, characterized in that: include A flue gas pretreatment unit, the flue gas pretreatment unit includes a flue gas pretreatment tower, and the flue gas pretreatment tower is used to pretreat the flue gas; The hollow fiber membrane reactor absorption unit is connected to the flue gas pretreatment tower. The hollow fiber membrane reactor absorption unit includes a hollow fiber membrane reactor. The hollow fiber membrane reactor is connected to the flue gas pretreatment tower. The flue gas pretreated by the flue gas pretreatment tower is pressurized and enters the hollow fiber membrane reactor to contact with the alcohol amine absorbent in the hollow fiber membrane reactor to remove CO2 in the flue gas. The flue gas heat exchange unit is connected to the flue gas pretreatment tower and the hollow fiber membrane reactor respectively. The alcohol amine rich liquid that has absorbed CO2 after being treated by the hollow fiber membrane reactor is heated by the high-temperature flue gas from the ship engine in the flue gas heat exchange unit. The cooled flue gas enters the flue gas pretreatment tower for pretreatment. The multi-stage flash desorption unit is connected to the flue gas heat exchange unit. The alcohol amine rich liquid that has absorbed CO2 after being heated by the flue gas heat exchange unit is adiabatically flashed in the multi-stage flash desorption unit. The CO2 loaded in the alcohol amine rich liquid is removed step by step. The alcohol amine lean liquid from which CO2 has been removed is cooled by the flue gas heat exchange unit and then refluxed to the hollow fiber membrane reactor for circulation. The CO2 compression and liquefaction unit is connected to the hollow fiber membrane reactor and the multi-stage flash desorption unit respectively. The CO2 gas obtained after being treated by the multi-stage flash desorption unit and the separated fresh water after cooling enter the hollow fiber membrane reactor. The CO2 gas is compressed and liquefied in the CO2 compression and liquefaction unit; The CO2 storage and transfer unit is connected to the CO2 compression and liquefaction unit. The CO2 storage and transfer unit includes a CO2 storage tank connected to the CO2 compression and liquefaction unit and a CO2 transfer unit connected to the CO2 storage tank. The liquid CO2 treated by the CO2 compression and liquefaction unit is stored in the CO2 storage tank and transported to the shore for processing by the CO2 transfer unit.

2. The compact ship exhaust carbon dioxide capture system according to claim 1, characterized in that: The flue gas pretreatment unit also includes a seawater pump connected to the first inlet of the flue gas pretreatment tower; A seawater supply valve is provided between the flue gas pretreatment tower and the seawater pump; A first water quality detector is arranged between the seawater pump and the seawater supply valve; A second flue gas supply valve is arranged at the second inlet of the flue gas pretreatment tower; A third flue gas supply valve is arranged at the first outlet of the flue gas pretreatment tower; The second water quality detector is arranged at the second outlet of the flue gas pretreatment tower.

3. The compact ship exhaust carbon dioxide capture system according to claim 1, characterized in that: The bottom inlet of the hollow fiber membrane reactor is connected to the first outlet of the flue gas pretreatment tower. The hollow fiber membrane reactor includes a shell, a plurality of hollow fiber membranes arranged in the shell and a metal screen arranged at both ends of the hollow fiber membranes, and the inner diameter of the metal screen is larger than the outer diameter of the hollow fiber membrane.

4. The compact ship exhaust carbon dioxide capture system according to claim 3, characterized in that: The hollow fiber membrane is made of polypropylene, polyvinylidene fluoride or polytetrafluoroethylene, with an average pore size of 0.01 to 0.1 μm and a porosity of more than 50%.

5. The compact ship exhaust carbon dioxide capture system according to claim 1, characterized in that: The flue gas heat exchange unit includes A rich liquid pump, wherein the inlet of the rich liquid pump is connected to the hollow fiber membrane reactor; A lean-rich liquid heat exchanger, wherein a first inlet of the lean-rich liquid heat exchanger is connected to an outlet of a rich liquid pump; A lean liquid cooler, wherein the lean liquid cooler inlet is connected to the first outlet of the lean-rich liquid heat exchanger, and the lean liquid cooler outlet is connected to the hollow fiber membrane reactor; A lean liquid pump, wherein the outlet of the lean liquid pump is connected to the second inlet of the lean and rich liquid heat exchanger; A flue gas heat exchanger, wherein the first inlet of the flue gas heat exchanger is connected to the ship engine, the second inlet of the flue gas heat exchanger is connected to the second outlet of the lean-rich liquid heat exchanger, and the first outlet of the flue gas heat exchanger is connected to the second inlet of the flue gas pretreatment tower; The first flue gas supply valve is arranged between the flue gas heat exchanger and the ship engine.

6. The compact ship exhaust carbon dioxide capture system according to claim 5, characterized in that: The multi-stage flash desorption unit comprises a primary flash tank, a secondary flash tank and a tertiary flash tank which are connected in sequence, wherein the inlet of the primary flash tank is connected to the second outlet of the flue gas heat exchanger, the bottom outlet of the primary flash tank is connected to the inlet of the secondary flash tank, the bottom outlet of the secondary flash tank is connected to the inlet of the tertiary flash tank, and the bottom outlet of the tertiary flash tank is connected to the inlet of the lean liquid pump.

7. The compact ship exhaust carbon dioxide capture system according to claim 6, characterized in that: The CO2 compression and liquefaction unit includes A multi-stage CO2 compressor, wherein a first inlet of the multi-stage CO2 compressor is connected to an upper outlet of a first-stage flash tank, a second inlet of the multi-stage CO2 compressor is connected to an upper outlet of a second-stage flash tank, and a third inlet of the multi-stage CO2 compressor is connected to an upper outlet of a third-stage flash tank; A CO2 cooler, wherein the inlet of the CO2 cooler is connected to the outlet of the multi-stage CO2 compressor; Gas-liquid separation tank, the inlet of the gas-liquid separation tank is connected to the outlet of the CO2 cooler, and a liquid level sensor is provided on the gas-liquid separation tank; A fresh water pump, wherein the fresh water pump inlet is connected to the first outlet of the gas-liquid separation tank, and the fresh water pump outlet is connected to the hollow fiber membrane reactor; A fresh water regulating valve is arranged between the fresh water pump and the hollow fiber membrane reactor; A CO2 compression and liquefaction device, wherein the first inlet of the CO2 compression and liquefaction device is connected to the second outlet of the gas-liquid separation tank, the second inlet of the CO2 compression and liquefaction device is connected to the first outlet of the CO2 storage tank, and the outlet of the CO2 compression and liquefaction device is connected to the inlet of the CO2 storage tank.

8. The compact ship exhaust carbon dioxide capture system according to claim 1, characterized in that: The CO2 storage and transfer unit also includes A pressure sensor is installed on the CO2 storage tank; A gaseous CO2 reflux regulating valve is arranged between the second inlet of the CO2 compression and liquefaction device and the first outlet of the CO2 storage tank; A liquid CO2 supply pump connected to the second outlet of the CO2 storage tank; A first liquid CO2 supply valve is arranged at the inlet of the CO2 storage tank; The second liquid CO2 supply valve is arranged between the CO2 transfer unit and the liquid CO2 supply pump.

9. The capture method of the compact ship exhaust carbon dioxide capture system according to any one of claims 1 to 8, characterized in that: The following steps are involved: The high-temperature flue gas from the ship engine passes through the flue gas heat exchange unit to heat the alcohol amine rich liquid, and then enters the flue gas pretreatment tower, where it comes into contact with the seawater entering the flue gas pretreatment tower to cool down, remove dust and desulfurize. The flue gas treated in the flue gas pretreatment tower is pressurized and then enters the hollow fiber membrane reactor, where it contacts with the alcohol amine absorbent in the hollow fiber membrane reactor to remove CO2 from the flue gas; The alcohol amine rich liquid that has absorbed CO2 enters the flue gas heat exchange unit for heating and then enters the multi-stage flash desorption unit for adiabatic flash evaporation to remove CO2 step by step; The CO2 gas removed by the multi-stage flash desorption unit enters the CO2 compression and liquefaction unit for compression and liquefaction, and the liquid CO2 is transported to the CO2 storage tank for storage. When the ship docks at the port, the liquid CO2 is transported to the CO2 transfer unit, and then transported to the shore for treatment.

10. The capture method of the compact ship exhaust carbon dioxide capture system according to claim 9, characterized in that: The amine lean liquid from which CO2 is removed by the multi-stage flash desorption unit is cooled by the flue gas heat exchange unit and then refluxed to the hollow fiber membrane reactor for circulation.

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