A co2 capture recovery system and method for a deep sea ore collection vessel

Abstract

The application provides a CO2 capture and recovery system and method for a deep-sea ore collecting ship, and belongs to the field of combustion product removal treatment and recovery; the system comprises an air suction hood, which is sequentially connected with a tubular heat exchanger and a screw expander; high-temperature water vapor obtained after primary cooling of the tubular heat exchanger is used for heating separation of CO2; the screw expander is connected with a turbine compressor, and kinetic energy obtained after secondary cooling is used for driving the turbine compressor; cooled flue gas enters an absorption tower and a regeneration tower in sequence, and CO2 in the flue gas is absorbed and desorbed; heat absorbed by the tubular heat exchanger is used for heating desorbed CO2 gas; after the CO2 gas is discharged, the CO2 gas is cooled and cooled down under the action of a condensing device, and then enters the turbine compressor for pressurization treatment, so that liquid CO2 is obtained and stored. The application solves the problem of the source of liquid carbon dioxide for deep-sea ore collection while reducing carbon emission; and heat of flue gas is recycled through the heat exchanger and the screw expander, so that energy required for carbon dioxide collection is effectively provided.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of combustion material cleaning treatment and recovery, and is applied to the recycling of combustion gas of a ship, in particular to a CO2 capture and recovery system and method for a deep-sea ore collection ship. BACKGROUND

[0002] With the in-depth research on marine resources and the progress of development technology, deep-sea mining has become one of the global focuses. The collection device, as one of the core mining equipment, has always been the focus of attention. At present, the hydraulic collection method is the most widely used. The hydraulic method is a kind of collection method that uses water jet to hit the nodule particles on the seabed surface to strip the polymetallic nodule ore from the mud surface, and then uses the pressure difference to complete the suction work. However, this mechanism has the disadvantages of high energy consumption, easy to be affected by the seabed microtopography, and large disturbance to the seabed environment, mainly manifested as: the water flow needs to have a large energy when it is shot out, and the energy of the water jet is dissipated quickly in the process of traveling due to the influence of viscosity; the impact range of the water jet on the soft sediment is large, which produces a large-scale plume and causes the suffocation of marine organisms.

[0003] CN115749786 A discloses a supercritical CO2 jet collection and tail flow processing system, which includes a jet collection device, a pump suction pipeline, a separation and storage device, and a tail flow processing unit. The jet collection device includes an anti-overflow cover and a high-pressure jet nozzle with heating function. The bottom of the anti-overflow cover is of an open structure. The high-pressure jet nozzle has two groups, which are oppositely arranged inside the anti-overflow cover and can spray supercritical CO2 to the inside of the anti-overflow cover. The front end of the pump suction pipeline is fixedly connected with the top of the anti-overflow cover, and the rear end is fixedly connected with the separation and storage device. The tail flow processing unit is arranged below the separation and storage device and is fixedly and sealingly connected with the bottom of the front end of the separation and storage device. The application realizes the collection of polymetallic nodules, solves the damage of plume diffusion to the marine ecological environment, and ensures the normal operation of subsequent mining operations.

[0004] The above patent is an improvement on the hydraulic jet method, which uses liquid carbon dioxide jet instead of water jet. Liquid CO2 has the characteristics of higher density than seawater and smaller viscosity. Using liquid CO2 jet can achieve high jet efficiency, low energy consumption, and small plume range, which can greatly reduce the disturbance and damage to the marine environment. However, the source of liquid carbon dioxide is not proposed. The mining mother ship needs to provide carbon dioxide raw materials for this collection method, and the problem of carbon energy supply needs to be solved. SUMMARY

[0005] In order to solve the problems in the background art, the application designs a scheme that can be applied to the liquid carbon dioxide collection of the mining mother ship.

[0006] The first aspect of the present application provides a CO2 capture and recovery system for a deep-sea ore collection ship, comprising a gas suction hood for absorbing the flue gas emitted by the ship, a tubular heat exchanger and a screw expander connected in sequence behind the gas suction hood, respectively used for primary cooling and secondary cooling of the flue gas, the tubular heat exchanger obtains high-temperature water vapor after primary cooling for subsequent heating separation of CO2, the screw expander is connected with a turbine compressor for pressurizing treatment of CO2, and the kinetic energy obtained during secondary cooling is used to drive the turbine compressor.

[0007] The flue gas after secondary cooling is discharged from the screw expander into an absorption tower, the absorption tower is provided with a monoethanolamine solution for dissolving and absorbing CO2 gas, and becomes rich-amine solution after absorbing CO2 gas; the absorption tower is connected with a regeneration tower, the heat absorbed by the tubular heat exchanger is used to heat and desorb CO2 gas from the rich-amine solution entering the regeneration tower; the regeneration tower is connected with a condensing device, the CO2 gas discharged from the regeneration tower is cooled and cooled down under the action of the condensing device, and then enters the turbine compressor for pressurizing treatment, to obtain liquid CO2 and store it in a storage tank.

[0008] Preferably, a water washing pretreatment device is further arranged between the screw expander and the absorption tower, the water washing pretreatment device comprises a spray head and a water pump, the spray head sprays water from the water pump to the flue gas to remove the gas easily soluble in water in the flue gas, so as to avoid the reaction with the monoethanolamine solution absorbent to generate impurities.

[0009] Preferably, the absorption tower comprises a flue gas inlet, an absorbent inlet, a tower bottom outlet and a tower top outlet; the flue gas after cooling and desulfurization enters from the flue gas inlet, the carbon dioxide in the flue gas reacts with the monoethanolamine solution flowing from the absorbent inlet to generate rich-amine solution which flows out from the tower bottom outlet under the pumping action, and the flue gas after decarburization is discharged to the atmosphere layer from the tower top outlet.

[0010] Preferably, a pump suction device is arranged between the absorption tower and the regeneration tower; the regeneration tower comprises a rich-amine liquid inlet, a lean-amine liquid outlet, a CO2 outlet, a heating plate, a filter plate and a water vapor inlet; a solution cavity is formed between the heating plate and the filter plate, the rich-amine liquid enters the solution cavity from the rich-amine liquid inlet under the action of the pump suction device, the high-temperature water vapor generated by the tubular heat exchanger enters the bottom of the regeneration tower through the water vapor inlet, the rich-amine liquid in the solution cavity is heated and desorbed to CO2 gas by the heating plate, the CO2 gas is discharged from the CO2 outlet through the filter plate; the lean-amine liquid after desorption is discharged from the lean-amine liquid outlet of the regeneration tower.

[0011] Preferably, the lean amine liquid purification device comprises an activated carbon filter and a first condenser; the lean amine liquid first enters the activated carbon filter to remove solid suspensions, and then enters the first condenser to reduce the temperature to below 10 DEG C, so as to precipitate heat-stable salts and remove impurities; and the purified lean amine liquid is reused after entering the absorption tower.

[0012] Preferably, the regeneration tower is connected with a heat exchanger; the rich amine liquid inlet and the lean amine liquid outlet are connected with the heat exchanger, so that the rich amine liquid flowing into the regeneration tower and the lean amine liquid flowing out of the regeneration tower are subjected to heat exchange before flowing in and out.

[0013] Preferably, the bottom of the regeneration tower is provided with a temperature control device, which comprises a temperature controller, a thermometer, a second condenser and an evaporator.

[0014] The thermometer measures the temperature of the steam heating the bottom of the regeneration tower; if the measured temperature is higher than the upper limit of the preset temperature range, the temperature controller controls the first switch to be closed, so that the second condenser is connected to cool the regeneration tower until the temperature reaches a certain preset temperature, and then the switch is disconnected; if the temperature is lower than the lower limit of the preset temperature range, the temperature controller controls the second switch to be closed, so that the evaporator is connected to heat the regeneration tower, and when the temperature reaches a certain preset temperature, the second switch is automatically disconnected.

[0015] The second aspect of the application provides a CO2 capture and recovery method for a deep-sea ore collection ship, comprising the following processes:

[0016] The flue gas discharged by the ship is obtained through the air suction hood;

[0017] The flue gas is cooled, including a primary cooling process and a secondary cooling process; the primary cooling process is cooled by a heat exchanger to obtain heat, which is used for subsequent heating separation of CO2; the secondary cooling process is driven by a screw expander to obtain kinetic energy, which is used to drive a compressor to pressurize the separated CO2;

[0018] The cooled flue gas is dissolved and absorbed by a monoethanolamine solution, and becomes rich amine liquid after absorbing CO2 gas;

[0019] The heat absorbed by the heat exchanger is used to heat and desorb CO2 gas from the rich amine liquid;

[0020] The desorbed CO2 gas is cooled and then enters a compressor for pressurization treatment to obtain liquid CO2 and storage.

[0021] Preferably, the process further comprises a water washing pretreatment process; the flue gas after secondary cooling is first sprayed with water to remove gases that are easily soluble in water in the flue gas, so as to avoid interference of impurities generated by reaction with the monoethanolamine solution absorbent, and then the monoethanolamine solution is used for CO2 dissolution and absorption.

[0022] Preferably, the process further comprises the following steps:

[0023] The lean amine solution after heating and desorbing CO2 gas is purified and reused; the lean amine solution first enters an activated carbon filter to remove solid suspensions, and then enters a condenser to reduce the temperature to below 10 DEG C, so as to precipitate heat stable salts and remove impurities; the purified lean amine solution is reused as a monoethanolamine solution.

[0024] Preferably, the heat exchange absorber further comprises a temperature control device for controlling the heating temperature, so that the heating temperature is always maintained within a certain temperature range.

[0025] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0026] 1. Reducing carbon emissions, protecting the ecological environment, and solving the energy source problem of liquid carbon dioxide; the present scheme can reduce the content of carbon dioxide emitted into the atmosphere, thereby reducing the risk of climate change, reducing the frequency and severity of extreme weather events, and ocean acidification; actively promoting the realization of the "double carbon" goal, while solving the problem of carbon energy supply; the present application can provide carbon energy demand for carbon dioxide jet, and further exploit deep-sea polymetallic nodules.

[0027] 2. Realizing carbon utilization in place and saving costs; if the carbon dioxide collected during the single-line operation of the ship from land to sea is transported back to land for utilization, transportation and storage costs will be generated; realizing carbon utilization in the sea helps to reduce costs.

[0028] 3. Recovering heat from ship exhaust gas, solving the problem of carbon capture energy consumption; the temperature of the exhaust gas emitted by the ship is 300-500 DEG C, containing a high amount of heat, which can be recovered and utilized by a heat exchanger and a screw expander, providing the energy required for the present scheme to collect carbon dioxide; thus, the energy supply problem does not affect the operation of the ship.

[0029] 4. Reducing the consumption of absorbents due to oxidative degradation and thermal degradation reactions, and ensuring absorption efficiency; the closed design of the air suction hood prevents air from mixing with the flue gas, avoiding oxidative degradation reactions between oxygen in the air and the absorbent; the water washing pretreatment device pretreats the flue gas to remove gases that are easily soluble in water, avoiding interference with the absorbent reaction with the monoethanolamine solution; the temperature control device controls the heating and cooling of the steam temperature in the regeneration tower, avoiding excessive thermal degradation reactions caused by high temperature and excessive consumption of absorbents. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the following description is only one embodiment of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0031] Figure 1 is the overall structure schematic diagram of the CO2 capture and recovery system of the present application;

[0032] Figure 2 is the overall process schematic diagram of the CO2 capture and recovery method of the present application;

[0033] Figure 3 is the structure schematic diagram of the air suction hood of the present application;

[0034] Figure 4 is the structure schematic diagram of the flue gas heat utilization of the present application;

[0035] Figure 5 is the structure schematic diagram of the temperature control device;

[0036] Figure 6 is the schematic diagram of the liquid CO2 used for jet flow collection process;

[0037] Figure 7 is the structure schematic diagram of the liquid CO2 used for jet flow collection.

[0038] 1. Air suction hood; 2. Exhaust fan; 3. Tubular heat exchanger; 4. Screw expander; 5. Water washing pretreatment device; 6. Absorption tower; 61. Flue gas inlet; 62. Absorbent inlet; 63. Tower bottom outlet; 64. Tower top outlet; 7. Pump suction device; 8. Heat exchanger; 9. Regeneration tower; 91. Rich amine liquid inlet; 92. Lean amine liquid outlet; 93. CO2 outlet; 94. Heating plate; 95. Filter plate; 96. Water vapor inlet; 10. Condensing device; 11. Turbine compressor; 12. Temperature control device; 121. Temperature controller; 122. Thermometer; 123. Second condenser; 124. Evaporator; 13. Activated carbon filter; 14. First condenser; 15. Storage tank. DETAILED DESCRIPTION

[0039] The technical solutions in the specific embodiments of the present application will be described clearly and completely in combination with the drawings in the present application.

[0040] The application provides a CO2 capture and recovery system and method for a deep-sea ore collection ship.

[0041] The embodiment provides a specific implementation mode of a CO2 capture and recovery system and method for a deep-sea ore collection ship, as shown in Figure 1 and Figure 2 .

[0042] The air suction hood 1 is used for absorbing the flue gas emitted by the ship. Figure 3 As shown in the figure, the air suction hood 1 is designed to be airtight and has the function of isolating air.

[0043] The temperature of the flue gas emitted by the ship is in the range of 300-500 DEG C, and the flue gas needs to be cooled before carbon recovery. Under the action of the exhaust fan 2, the flue gas is sucked and cooled.

[0044] Specifically, the volume expansion of the flue gas drives the male and female screws to rotate in opposite directions, so that the thermal energy is converted into mechanical energy.

[0045] The cooled flue gas is discharged from the gear groove of the screw expander 4 and enters the flue gas water washing pretreatment device 5.

[0046] The device is composed of a spray head and a water pump.

[0047] The specific structure of the absorption tower 6 is shown in Figure 1As shown, the tower includes a flue gas inlet 61, an absorbent inlet 62, a bottom outlet 63, and a top outlet 64. The temperature of the flue gas after cooling and desulfurization is 40℃-60℃, which is conducive to the absorption of carbon dioxide by the monoethanolamine solution. It enters from the flue gas inlet 61. The carbon dioxide in the flue gas reacts with the monoethanolamine solution flowing in from the absorbent inlet 62 to form carbamate, which flows out from the bottom outlet 63 under the suction of the pump. The ethanolamine solution loaded with carbon dioxide is called amine-rich solution. The decarbonized flue gas is discharged into the atmosphere from the top outlet 64.

[0048] The rich amine solution is heated by the heat exchanger 8 under the action of the pump suction device 7 and enters the regeneration tower 9. Water vapor is used as a heat source to drive the rich amine solution, thereby desorbing carbon dioxide gas and leaving the decarbonized amine solution, which is called the lean amine solution.

[0049] A pump suction device 7 is installed between the absorption tower 6 and the regeneration tower 9. The regeneration tower 9 includes a rich amine liquid inlet 91, a lean amine liquid outlet 92, a CO2 outlet 93, a heating plate 94, a filter plate 95, and a steam inlet 96. A solution chamber is formed between the heating plate 94 and the filter plate 95. Under the action of the pump suction device 7, the rich amine liquid enters the solution chamber from the rich amine liquid inlet 91. The high-temperature steam generated by the tubular heat exchanger 3 enters the bottom of the regeneration tower 9 through the steam inlet 96. The heating plate 94 heats the rich amine liquid in the solution chamber and desorbs CO2 gas. The CO2 gas passes through the filter plate 95 and is discharged from the CO2 outlet 93. The desorbed lean amine liquid is discharged from the regeneration tower from the lean amine liquid outlet 92.

[0050] The regeneration tower 9 is connected to a heat exchanger 8; the rich amine liquid inlet 91 and the lean amine liquid outlet 92 are both connected to the heat exchanger 8, so that the rich amine liquid flowing into the regeneration tower 9 and the lean amine liquid flowing out of the regeneration tower 9 exchange heat before flowing in and out.

[0051] CO2 forms a relatively weak salt with monoethanolamine, which can be desorbed at higher temperatures (above 105 °C), thereby achieving the capture of carbon dioxide and the recycling of amine solution; however, the energy consumed by desorption is relatively large, and if the energy consumption for desorption is provided by the ship's power supply device, it may have a certain impact on the operation of other structures of the ship; the present invention uses waste heat recovery from flue gas to provide energy consumption.

[0052] Specifically, such as Figure 4 As shown, the flue gas passes through the tubular heat exchanger 3 and exchanges heat with the low-temperature water medium. The low-temperature water absorbs the heat of the flue gas and turns into high-temperature water vapor, which enters the bottom of the regeneration tower 9 for steam heating to achieve the separation of carbon dioxide. The carbon dioxide after heating and separation is discharged from the CO2 outlet 93 of the regeneration tower 9 and stored in the form of liquid carbon dioxide after cooling and compression.

[0053] Specifically, the high-temperature carbon dioxide is cooled to about 20℃ by the condensing device 10, and then enters the turbine compressor 11 for pressurization treatment, so as to reach the condition of being converted into liquid carbon dioxide; finally, the carbon dioxide is stored in the storage tank 15 in the form of liquid.

[0054] Carbon dioxide compression is one of the reasons for high energy consumption of carbon capture, and the energy consumption required for compression is also from the heat recovered from the flue gas, such as Figure 4 As shown in the figure, the flue gas enters the screw expander 4 from the tubular heat exchanger 3, first enters the screw groove in the machine, and drives the screw to rotate. With the rotation of the screw, the volume continuously increases, and the steam is depressurized, cooled and expanded (or flashed) to do work, and finally the gas is discharged. The output power from the male screw of the main shaft drives the turbine compressor 11 to work.

[0055] At the same time, the system also includes a temperature control device. Thermal degradation is caused by high temperature and high partial pressure of acid gas, and mainly occurs in the bottom of the regeneration tower. Thermal degradation substances will polymerize into viscous substances similar to resin at high temperature, causing an increase in pollutants, which is not conducive to the recycling of amine solution; when the tower bottom temperature is higher than 120℃, the thermal degradation begins to gradually increase; therefore, the temperature of the steam heat source in the regeneration tower needs to be controlled;

[0056] Specifically, the bottom of the regeneration tower is connected with the temperature control device 12, as shown in the figure, the temperature control device 12 includes a temperature controller 121, a thermometer 122, a second condenser 123 and an evaporator 124; Figure 5

[0057] The thermometer 122 measures the temperature of the heating steam at the bottom of the regeneration tower 9; if the measured temperature is higher than the upper limit of the preset temperature range, the temperature controller 121 controls the first switch 125 to close, and connects the second condenser 123 to cool the regeneration tower 9 until the temperature reaches a certain preset temperature, and the switch is disconnected; if the temperature is lower than the lower limit of the preset temperature range, the temperature controller 121 controls the second switch 126 to close, and connects the evaporator 124 to heat the regeneration tower 9, and when the temperature reaches a certain preset temperature, the second switch 126 is automatically disconnected.

[0058] Further, because the temperature control of the temperature controller 121 will have small amplitude fluctuations, a floating space is needed, so the target temperature of the temperature controller 121, i.e. the above-mentioned certain preset temperature, is set to 110℃, and the preset temperature range is 110-120℃; which can prevent the influence of serious degradation caused by too high temperature and low desorption efficiency caused by too low temperature.

[0059] ​After the lean amine liquid flows out from the bottom outlet 92 of the regeneration tower 9, it passes through the heat exchanger 8 to transfer heat to the rich amine liquid for cooling; then it is purified to continuously remove suspended solids and thermally stable salts and other impurities from the amine liquid, thereby maintaining the cleanliness of the amine liquid system and the absorption efficiency of the amine liquid.

[0060] Specifically, the lean amine solution contains suspended solids and thermally stable salts, which can seriously affect the quality control of the lean amine solution, the stable operation of the equipment, and the corrosion damage to the equipment. Therefore, it needs to be purified. The lean amine solution purification device consists of an activated carbon filter 13 and a first condenser 14.

[0061] Furthermore, ZC activated carbon, as the adsorption activated carbon for the pretreatment of lean amine solution, has the advantages of good adsorption effect and low price, and can effectively remove solid suspended matter. After pretreatment, the lean amine solution enters the second condenser to reduce the temperature to below 10°C, which promotes the precipitation of thermally stable salts and removes impurities. After removing impurities, the lean amine solution is heated to about 40°C and can enter the absorption tower for reuse.

[0062] After carbon dioxide capture and storage is completed, it is transported to the deep sea via pipelines to solve the energy supply problem for CO2 jets. The specific process is as follows: Figure 6 and Figure 7 As shown, the specific jet acquisition device and method are existing publicly available technologies, and will not be described in detail here.

[0063] The foregoing description, in conjunction with the accompanying drawings, fully illustrates specific embodiments of the invention to enable those skilled in the art to practice them. Some embodiments may include or replace parts and features of other embodiments. The scope of the embodiments of the invention encompasses the entire scope of the claims and all available equivalents thereof. In this invention, the terms "first," "second," etc., are used only to distinguish one element from another, without requiring or implying any actual relationship or order between these elements. In fact, a first element can also be referred to as a second element, and vice versa. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a structure, apparatus, or device comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a structure, apparatus, or device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the structure, apparatus, or device that includes said element. The various embodiments in this invention are described in a progressive manner, with each embodiment focusing on the differences from other embodiments; similar or identical parts between embodiments can be referred to interchangeably.

[0064] The terms "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like in the present application indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In the description herein, unless otherwise specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be a mechanical connection or an electrical connection, it can be a communication between two elements, it can be directly connected, or indirectly connected through an intermediate medium, and the specific meaning of the above terms can be understood by those skilled in the art according to the specific circumstances. In the present application, unless otherwise specified, the term "a plurality of" means two or more.

[0065] The above is only the preferred embodiment of the present application and is not intended to limit the present application. Those skilled in the art can make various modifications and changes to the present application, and those skilled in the art should understand that various modifications or changes or equivalent replacements and the like made by those skilled in the art on the basis of the technical solutions of the present application without creative labor should be included in the protection scope of the present application.

Claims

1. A CO2 capture recovery system for a deep sea ore collection vessel, characterized by: The application relates to a system for absorbing ship exhaust gas, which comprises a gas suction hood (1) for absorbing the exhaust gas, a tubular heat exchanger (3) and a screw expander (4) connected in sequence behind the gas suction hood (1) and used for primary cooling and secondary cooling of the exhaust gas respectively, the tubular heat exchanger (3) obtains high-temperature water vapor after primary cooling and is used for subsequent heating separation of CO2, the screw expander (4) is connected with a turbine compressor (11) for pressurizing treatment of the CO2, and the kinetic energy obtained during secondary cooling is used for driving the turbine compressor (11). The exhaust gas after secondary cooling is discharged from the screw expander (4) into an absorption tower (6), the absorption tower (6) is provided with a monoethanolamine solution for dissolving and absorbing CO2 gas, and the monoethanolamine solution becomes rich-amine solution after absorbing the CO2 gas; the absorption tower (6) is connected with a regeneration tower (9), heat absorbed by the tubular heat exchanger (3) is used for heating and desorbing the CO2 gas from the rich-amine solution entering the regeneration tower (9); the regeneration tower (9) is connected with a condensing device (10), the CO2 gas is cooled and cooled down under the action of the condensing device (10) after being discharged from the regeneration tower (9), and then enters the turbine compressor (11) for pressurizing treatment, so that liquid CO2 is obtained and stored in a storage tank (15); the liquid CO2 is transported to the deep sea through a conveying pipeline and is used for mining deep-sea polymetallic nodules.

2. A CO2 capture recovery system for a deep sea mining vessel as claimed in claim 1, characterised in that: The screw expander (4) and the absorption tower (6) are further provided with a water washing pretreatment device (5), the water washing pretreatment device (5) comprises a spraying head and a water pump, the spraying head sprays water provided by the water pump to the exhaust gas, removes water-soluble gas in the exhaust gas, and avoids the reaction of the monoethanolamine solution absorbent and the water-soluble gas to generate impurities.

3. A CO2 capture recovery system for a deep sea mining vessel as claimed in claim 2, characterised in that: The absorption tower (6) comprises a flue gas inlet (61), an absorbent inlet (62), a tower bottom outlet (63) and a tower top outlet (64); the flue gas after cooling and desulfurization enters from the flue gas inlet (61), carbon dioxide in the flue gas reacts with the monoethanolamine solution flowing from the absorbent inlet (62) to generate rich-amine solution which flows out from the tower bottom outlet (63) under the pumping action, and the flue gas after decarburization is discharged to the atmosphere layer from the tower top outlet (64).

4. A CO2 capture recovery system for a deep sea mining vessel as claimed in claim 1, characterized in that: A pump suction device (7) is arranged between the absorption tower (6) and the regeneration tower (9); the regeneration tower (9) comprises a rich-amine solution inlet (91), a lean-amine solution outlet (92), a CO2 outlet (93), a heating plate (94), a filtering plate (95) and a water vapor inlet (96); the heating plate (94) and the filtering plate (95) form a solution cavity, the rich-amine solution enters the solution cavity from the rich-amine solution inlet (91) under the action of the pump suction device (7), high-temperature water vapor generated by the tubular heat exchanger (3) enters the bottom of the regeneration tower (9) through the water vapor inlet (96), the rich-amine solution in the solution cavity is heated and desorbs CO2 gas through the heating plate (94), the CO2 gas is discharged from the CO2 outlet (93) through the filtering plate (95), and the lean-amine solution after desorption is discharged from the lean-amine solution outlet (92) of the regeneration tower.

5. A CO2 capture recovery system for a deep sea mining vessel as claimed in claim 4 wherein: The lean amine solution purification device comprises an activated carbon filter (13) and a first condenser (14); the lean amine solution first enters the activated carbon filter (13) to remove solid suspensions, and then enters the first condenser (14) to reduce the temperature to below 10℃, so as to promote the precipitation of heat stable salts and remove impurities; and the purified lean amine solution is reused after entering the absorption tower (6).

6. A CO2 capture recovery system for a deep sea mining vessel as claimed in claim 4 or 5 wherein: The heat exchanger (8) is connected to the rich amine solution inlet (91) and the lean amine solution outlet (92), so that the rich amine solution flowing into the regeneration tower (9) and the lean amine solution flowing out of the regeneration tower (9) are subjected to heat exchange before flowing in and out.

7. A CO2 capture recovery system for a deep sea mining vessel as claimed in claim 1, characterized in that: The temperature control device (12) comprises a temperature controller (121), a thermometer (122), a second condenser (123) and an evaporator (124); The thermometer (122) measures the temperature of the water vapor at the bottom of the regeneration tower (9); if the measured temperature is higher than the upper limit of the preset temperature range, the temperature controller (121) controls the first switch (125) to be closed, so that the second condenser (123) is turned on to cool the regeneration tower (9) until the temperature reaches a certain preset temperature, and the switch is turned off; if the temperature is lower than the lower limit of the preset temperature range, the temperature controller (121) controls the second switch (126) to be closed, so that the evaporator (124) is turned on to heat the regeneration tower (9), and when the temperature reaches a certain preset temperature, the second switch (126) is automatically turned off.

8. A CO2 capture recovery method for a deep sea ore collecting ship, characterized by, The process comprises the following steps: Obtaining the flue gas emitted by the ship through the air suction cover; Cooling the flue gas, including a primary cooling process and a secondary cooling process; the primary cooling process is cooled by a heat exchanger to obtain heat, which is used for subsequent heating separation of CO2; the secondary cooling process is driven by a screw expander to obtain kinetic energy, which is used to drive a compressor to pressurize the separated CO2; The cooled flue gas is dissolved and absorbed by a monoethanolamine solution, and becomes rich amine solution after absorbing CO2 gas; The heat absorbed by the heat exchanger heats the rich amine solution to desorb CO2 gas; The desorbed CO2 gas is cooled and then enters a compressor for pressurization treatment to obtain liquid CO2, which is stored and transported to the deep sea through a pipeline for mining of deep-sea polymetallic nodules.

9. A method for CO2 capture recovery for a deep sea mining vessel as claimed in claim 8, characterized by: The process further comprises a water washing pretreatment process, in which the flue gas after secondary cooling is first sprayed with water to remove gases that are easily soluble in water, so as to avoid interference with the monoethanolamine solution absorbent, and then the monoethanolamine solution is used for CO2 dissolution and absorption.

10. The CO2 capture recovery method for a deep sea mining vessel according to claim 8, wherein, The process further comprises the following steps: The lean amine solution after heating and desorbing CO2 gas is purified and reused; the lean amine solution first enters an activated carbon filter to remove solid suspensions, and then enters a condenser to reduce the temperature to below 10℃, so as to promote the precipitation of heat stable salts and remove impurities; and the purified lean amine solution is reused as a monoethanolamine solution.

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