A co2 capture system in a marine fuel flue gas

Abstract

The application discloses a CO2 capturing system in ship fuel flue gas, wherein the inlet of the flue gas pipeline of the flue gas CO2 heat exchanger is connected with high-temperature flue gas of a ship engine or a boiler, the outlet of the flue gas pipeline is connected with the flue gas inlet of a flue gas pretreatment unit, the inlet of the CO2 gas pipeline is aligned with the cooling area of a zeolite wheel, the outlet of the CO2 gas pipeline is aligned with the desorption area of the zeolite wheel, the flue gas outlet of the pretreatment unit is aligned with the adsorption area of the zeolite wheel, the high-temperature CO2 gas inlet of the CO2 distributor is aligned with the desorption area of the zeolite wheel, the inlet of the seawater cooler is connected with one high-temperature CO2 gas outlet of the CO2 distributor, the outlet is aligned with the adsorption area of the zeolite wheel, the other high-temperature CO2 gas outlet of the CO2 distributor is connected with a CO2 liquefaction unit, and the CO2 liquid outlet of the CO2 liquefaction unit is connected with a low-temperature CO2 liquid storage tank. The application has the advantages of simple structure, small space occupation, small investment and low operation cost.

Description

Technical Field

[0001] This invention relates to a CO2 capture system for ship fuel flue gas. Background Technology

[0002] The shipping industry today faces both known and unknown environmental and emissions regulations and requirements, such as the International Convention for the Prevention of Pollution from Ships (MARPOL) and the decarbonization targets of the International Maritime Organization (IMO). Currently, the market focuses on hydrogen, ammonia, LNG, and alcohols as future energy sources to ensure marine fuels meet future demands. According to a Clarkson report, new ship orders fell by nearly 50% in 2021, a significant reason being that shipowners were unsure which energy source to use to meet future shipping requirements, especially decarbonization requirements. In 2018, the IMO outlined its ambitious goals in its initial greenhouse gas (GHG) strategy. The targets were a 40% reduction in CO2 emissions from individual ships by 2030 and a 70% reduction by 2050; and a 50% reduction in total GHG emissions by 2050. These targets present many shipowners with a daunting task of achieving compliance. Shipowners may have to review operational efficiencies, such as navigation optimization, introduce advanced ship design technologies, implement reduced sailing speeds, and / or use alternative fuels with lower carbon footprints. This invention targets the collection of CO2 from post-combustion exhaust gases to achieve carbon reduction.

[0003] The commonly used carbon capture method is amine decarbonization, and the principle of amine decarbonization is as follows:

[0004] Flue gas is introduced into the pretreatment tower by an induced draft fan. After undergoing cooling, dust removal, deep desulfurization, and denitrification processes in the pretreatment tower, it is sent to the bottom of the absorption tower. Inside the absorption tower, it comes into countercurrent contact with the absorbent flowing down from the top, undergoing heat and mass transfer processes. The decarbonized flue gas is then discharged into the atmosphere. The absorbent in the absorption tower is a mixed amine liquid, utilizing the principle that amine liquid absorbs CO2 at low temperatures and releases CO2 at high temperatures. The absorbent acts as a lean solution in the absorption tower, absorbing CO2, and then enters the desorption tower. The rich solution regenerates the absorbent through heating and other methods, releasing CO2. The CO2 is then liquefied after being pressurized by a compressor and cooled by a cooler, and finally stored in a CO2 storage tank.

[0005] The following problems exist when using amine-based decarbonization systems in ships:

[0006] 1. Complex structure and large space occupation: The amine decarbonization system requires an absorption tower and a desorption tower, and the footprint of the two towers is relatively large; due to the limited space on ships, it is not suitable to install complex and large-volume equipment.

[0007] 2. High power consumption of equipment: The amine-based decarbonization system requires rich liquor pumps, lean liquor pumps, and compressors, all of which have significant power requirements. However, ships have limited mechanical power. Older ships adding decarbonization systems lack the spare power to supply the mechanical consumption of these devices. Newly built ships adding decarbonization systems require additional energy reserves to power these devices, leading to a significant reduction in usable cargo space and making it uneconomical.

[0008] 3. High investment and operating costs: In the amine-based decarbonization system, the initial investment cost accounts for 70% of the total investment cost of the absorption and desorption towers, while the operating cost accounts for 30%. The carbon capture cost ranges from $20 to $190 per tCO2. The regeneration of the absorbent in the desorption tower also requires a large amount of heat energy.

[0009] 4. The degradation products of the absorbent are harmful to the environment: After the absorbent degrades, it produces nitrosamines and ammonium nitrates. These substances diffuse into the atmosphere and have a great impact on the environment and human health. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and provide a CO2 capture system for ship fuel flue gas, which has a simple structure, small footprint, low investment, and low operating cost.

[0011] The objective of this invention is achieved as follows: a CO2 capture system for ship fuel flue gas, comprising a flue gas pretreatment unit, an induced draft fan zeolite rotor, a flue gas CO2 heat exchanger, a CO2 distributor, a seawater cooler, a CO2 liquefaction unit, and a cryogenic CO2 liquid storage tank; wherein,

[0012] The zeolite rotor is driven to rotate by a power mechanism. The lower part of the zeolite rotor is the adsorption zone, the upper left part of the zeolite rotor is the desorption zone, and the upper right part of the zeolite rotor is the cooling zone.

[0013] The flue gas CO2 heat exchanger is located in front of the zeolite rotor. The flue gas CO2 heat exchanger includes a flue gas pipeline and a CO2 gas pipeline. Each of the flue gas pipeline and the CO2 gas pipeline consists of multiple annular pipes, an inlet manifold, and an outlet manifold. The annular pipes are elongated microchannels. The multiple annular pipes of the flue gas pipeline and the multiple annular pipes of the CO2 gas pipeline are staggered and stacked. The flue gas inlet of the flue gas pipeline is connected to the high-temperature flue gas from the ship's engine or boiler, and the flue gas outlet of the flue gas pipeline is connected to the flue gas inlet of the flue gas pretreatment unit. The CO2 gas inlet of the CO2 gas pipeline is aligned with the cooling zone of the zeolite rotor, and the CO2 gas outlet of the CO2 gas pipeline is aligned with the desorption zone of the zeolite rotor.

[0014] The flue gas pretreatment unit and the induced draft fan are arranged sequentially behind the zeolite rotor; the flue gas outlet of the flue gas pretreatment unit is aligned with the air inlet of the induced draft fan, and the air outlet of the induced draft fan is aligned with the adsorption zone of the zeolite rotor.

[0015] The CO2 distributor is located behind the zeolite rotor, and the CO2 distributor has one high-temperature CO2 gas inlet and two high-temperature CO2 gas outlets; the high-temperature CO2 gas inlet is aligned with the desorption zone of the zeolite rotor.

[0016] The seawater cooler is located behind the zeolite rotor. The inlet of the seawater cooler is connected to a high-temperature CO2 gas outlet of the CO2 distributor, and the outlet of the seawater cooler is aligned with the cooling zone of the zeolite rotor.

[0017] The CO2 gas inlet of the CO2 liquefaction unit is connected to another high-temperature CO2 gas outlet of the CO2 distributor;

[0018] The cryogenic CO2 liquid storage tank is connected to the CO2 liquid outlet of the CO2 liquefaction unit.

[0019] The CO2 capture system for ship fuel flue gas described above, wherein the flue gas pretreatment unit includes a flue gas pretreatment spray layer, an absorbent spray layer, and a water washing spray layer.

[0020] The aforementioned CO2 capture system for ship fuel flue gas includes a CO2 liquefaction unit that is a thermoacoustic refrigeration unit and comprises a thermoacoustic engine, a low-temperature heat exchanger, a high-temperature heat exchanger, and a regenerator connected between the low-temperature and high-temperature heat exchangers. The thermoacoustic engine generates sound waves powered by the high-temperature flue gas from the ship's engine or boiler. The high-temperature flue gas enters the flue gas inlet of the flue gas pretreatment unit after passing through the thermoacoustic engine. The low-temperature heat exchanger receives the heat converted from the sound waves, and the CO2 gas inlet of the low-temperature heat exchanger is connected to another high-temperature CO2 gas outlet of the CO2 distributor.

[0021] The CO2 capture system for ship fuel flue gas of the present invention has the following characteristics:

[0022] 1. Simple system structure and small space occupation: There is no need to equip the CO2 capture system of this invention with an absorption tower and a desorption tower. The CO2 capture system of this invention only has one zeolite rotor. The zeolite rotor highly integrates the adsorption zone and the desorption zone, occupies little planar space, and saves a lot of cargo space for ships.

[0023] 2. Fewer power components, requiring virtually no additional power from the ship: The conversion of the adsorbent in the zeolite rotor does not require pump transportation, only a small amount of power to be provided to the zeolite rotor; there is no compressor, which greatly reduces energy consumption, making it very suitable for existing old ship retrofit projects; at the same time, it is also suitable for new ships. When a new ship needs to add the CO2 capture system of this invention, there is no need to add additional energy storage space or bear additional decarbonization costs.

[0024] 3. Low investment and low operating costs: The CO2 capture system of this invention has a simple structure and low initial investment cost. It has virtually no power components and no additional consumption during operation, making it easy to maintain. It mainly utilizes the waste heat of ship engines or boilers, which achieves energy conservation and emission reduction while reducing operating costs, in line with social development trends.

[0025] 4. Adsorbed zeolite has good thermal stability and does not produce harmful degradation substances: Adsorbed zeolite is an environmentally friendly product and does not have adverse effects on human health and the environment. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the CO2 capture system in ship fuel flue gas according to the present invention.

[0027] Figure 2 This is a schematic diagram of the zeolite rotor in the CO2 capture system of the present invention;

[0028] Figure 3 This is a perspective view of the flue gas CO2 heat exchanger in the CO2 capture system of the present invention;

[0029] Figure 4 This is a side view of the flue gas CO2 heat exchanger in the CO2 capture system of the present invention;

[0030] Figure 5 This is a schematic diagram of the CO2 liquefaction unit in the CO2 capture system of the present invention. Detailed Implementation

[0031] The invention will now be further described with reference to the accompanying drawings.

[0032] Please see Figures 1 to 5 The CO2 capture system in ship fuel flue gas of the present invention includes a flue gas pretreatment unit 1, an induced draft fan 2, a zeolite rotor 3, a flue gas CO2 heat exchanger 4, a CO2 distributor 5, a seawater cooler 6, a CO2 liquefaction unit 7, and a low-temperature CO2 liquid storage tank 8.

[0033] The zeolite rotor 3 is driven to rotate by the power mechanism 30. The lower part of the zeolite rotor 3 is the adsorption zone 31; the upper left part of the zeolite rotor 3 is the desorption zone 32; and the upper right part of the zeolite rotor 3 is the cooling zone 33.

[0034] A flue gas CO2 heat exchanger 4 is located in front of the zeolite rotor 3. The flue gas CO2 heat exchanger 4 includes a flue gas pipeline 41 and a CO2 gas pipeline 42. Each of the flue gas pipeline 41 and the CO2 gas pipeline 42 consists of multiple annular pipes, an inlet manifold, and an outlet manifold. The annular pipes adopt elongated oval microchannels. The multiple annular pipes of the flue gas pipeline 41 and the multiple annular pipes of the CO2 gas pipeline 42 are staggered and superimposed. The flue gas inlet 411 of the flue gas pipeline 41 is connected to the high-temperature flue gas of the ship's engine or boiler, and the flue gas outlet 412 of the flue gas pipeline 41 is connected to the flue gas inlet of the flue gas pretreatment unit 1. The CO2 gas inlet 421 of the CO2 gas pipeline 42 is aligned with the cooling zone 33 of the zeolite rotor 3, and the CO2 gas outlet 422 of the CO2 gas pipeline 42 is aligned with the desorption zone 32 of the zeolite rotor 3.

[0035] The flue gas pretreatment unit 1 and the induced draft fan 2 are arranged sequentially behind the zeolite rotor 3; the flue gas pretreatment unit 1 includes a flue gas pretreatment spray layer, an absorbent spray layer and a water washing spray layer; the flue gas outlet of the flue gas pretreatment unit 1 is aligned with the air inlet of the induced draft fan 2; the air outlet of the induced draft fan 2 is aligned with the adsorption zone 31 of the zeolite rotor 3.

[0036] The CO2 distributor 5 is located behind the zeolite rotor 3. The CO2 distributor 5 has a high-temperature CO2 gas inlet and two high-temperature CO2 gas outlets. The high-temperature CO2 gas inlet is aligned with the desorption zone 32 of the zeolite rotor 3.

[0037] The seawater cooler 6 is located behind the zeolite rotor 3. The inlet of the seawater cooler 6 is connected to a high-temperature CO2 gas outlet of the CO2 distributor 5. The outlet of the seawater cooler 6 is aligned with the cooling zone 33 of the zeolite rotor 3.

[0038] CO2 liquefaction unit 7 is a thermoacoustic refrigeration machine and includes a thermoacoustic engine 70, a low-temperature heat exchanger 71, a high-temperature heat exchanger 73, and a regenerator 72 connected between the low-temperature heat exchanger 71 and the high-temperature heat exchanger 73. The thermoacoustic engine 70 generates sound waves by being powered by the high-temperature flue gas from a ship engine or boiler. The high-temperature flue gas enters the flue gas inlet of the flue gas pretreatment unit 1 after passing through the thermoacoustic engine 70. The low-temperature heat exchanger 71 receives the heat work converted from the sound waves. The CO2 gas inlet of the low-temperature heat exchanger 71 is connected to another high-temperature CO2 gas outlet of the CO2 distributor 5.

[0039] The low-temperature CO2 liquid storage tank 8 is connected to the CO2 liquid outlet of the low-temperature end heat exchanger 71 of the CO2 liquefaction unit 7.

[0040] The working principle of the CO2 capture system in ship fuel flue gas of the present invention is as follows:

[0041] High-temperature flue gas enters the flue gas pretreatment unit 1. After pretreatment, the high-temperature flue gas becomes low-temperature desulfurization and denitrification flue gas. It then enters the adsorption zone 31 of the zeolite rotor 3 via the induced draft fan 2. The zeolite rotor 3 adsorbs CO2 from the flue gas, and the low-temperature decarbonization flue gas is then discharged into the atmosphere. After the zeolite rotor 3 reaches CO2 saturation, it rotates to the desorption zone 32 driven by the power mechanism 30. After being heated by the flue gas CO2 heat exchanger 4, CO2 is released and discharged to the CO2 distributor 5. The CO2 in the CO2 distributor 5 is high-temperature CO2 gas, and the regenerated adsorbent in the zeolite rotor 3 also becomes a high-temperature adsorbent. Based on calculations and analysis, a portion of the high-temperature CO2 gas enters the seawater cooler 6, and the other portion is discharged to the CO2 liquefaction unit 7. CO2 gas cooled by seawater cooler 6 enters cooling zone 33 of zeolite rotor 3, cooling the high-temperature adsorbent of zeolite rotor 3 into a low-temperature adsorbent, bringing it into an adsorption-ready state. Simultaneously, this portion of CO2 gas then enters flue gas CO2 heat exchanger 4. The heat source for flue gas CO2 heat exchanger 4 is high-temperature flue gas from a ship's engine or boiler. After being heated by flue gas CO2 heat exchanger 4, the high-temperature flue gas becomes low-temperature flue gas and is discharged to flue gas pretreatment unit 1. The CO2 gas cooled from cooling zone 33 of zeolite rotor 3, after being heated by flue gas CO2 heat exchanger 4 (high-temperature flue gas), enters desorption zone 32 of zeolite rotor 3, heating the CO2-rich adsorbent and causing high-concentration CO2 gas to be precipitated and discharged to CO2 distributor 5. This cycle repeats continuously, with CO2 being continuously collected and stored, and a small portion of the CO2 serving as a circulating medium to power desorption.

[0042] The functions of the desorption zone 32, cooling zone 33, and adsorption zone 31 of the zeolite rotor 3 are rotated periodically. When the adsorption zone 31 of the zeolite rotor 3 is saturated with CO2, it switches to the desorption zone 32 of the zeolite rotor 3 to absorb heat from the zeolite and release CO2. At the same time, the desorption zone 32 of the zeolite rotor 3 switches to the cooling zone 33 of the zeolite rotor 3 to cool the zeolite and prepare for CO2 absorption. The cooling zone 33 of the zeolite rotor 3 switches to the adsorption zone 31 of the zeolite rotor 3 to adsorb CO2 from the zeolite, completing the CO2 adsorption and desorption cycle. This cycle repeats continuously to achieve flue gas decarbonization.

[0043] The flue gas CO2 heat exchanger 4 transfers heat through the metal wall of the pipe, and the CO2 is heated by the high temperature flue gas to the temperature required for the zeolite rotor 3 to release CO2.

[0044] CO2 liquefaction unit 7 is a thermoacoustic refrigerator, powered by the waste heat of high-temperature flue gas from a ship's engine or boiler. The thermoacoustic refrigerator converts heat energy into sound energy, and then uses this sound energy to achieve refrigeration, converting gaseous CO2 into liquid and storing it in a low-temperature CO2 liquid storage tank 8. High-temperature flue gas passes through the thermoacoustic engine 70, providing power to generate sound waves. The initial temperature of the gas particles 720 in the regenerator 72 is lower than the temperature of the low-temperature heat exchanger 71. The gas particles 720 absorb heat in the low-temperature heat exchanger 71, and then move towards one end of the high-temperature heat exchanger 73 under the influence of sound waves. During this movement, the gas particles 720 undergo adiabatic compression, increasing both pressure and temperature. When the gas particles 720 reach one end of the high-temperature heat exchanger 73, their temperature is higher than that of the high-temperature heat exchanger 73, releasing heat to it. The heat is then absorbed by the high-temperature heat exchanger. The gas is carried away by the high-temperature heat exchanger 73; then, the gas particle 720 moves to one end of the low-temperature heat exchanger 71. The gas particle 720 undergoes adiabatic expansion, and both its pressure and temperature decrease. When the gas particle 720 moves to one end of the low-temperature heat exchanger 71, the temperature of the gas particle 720 is lower than the temperature of the low-temperature heat exchanger 71. The gas particle 720 absorbs the heat from the low-temperature heat exchanger 71, lowers the temperature of the low-temperature heat exchanger 71, and liquefies the gaseous CO2. The liquefied CO2 is then discharged to the low-temperature CO2 liquid storage tank 8.

[0045] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions should also fall within the scope of the invention and should be defined by the claims.

Claims

1. A CO2 capture system for ship fuel flue gas, comprising a flue gas pretreatment unit and a cryogenic CO2 liquid storage tank, characterized in that, The CO2 capture system also includes a zeolite rotor, a flue gas CO2 heat exchanger, an induced draft fan, a CO2 distributor, a seawater cooler, and a CO2 liquefaction unit; The zeolite rotor is driven to rotate by a power mechanism. The lower part of the zeolite rotor is the adsorption zone, the upper left part of the zeolite rotor is the desorption zone, and the upper right part of the zeolite rotor is the cooling zone. The flue gas CO2 heat exchanger is located in front of the zeolite rotor. The flue gas CO2 heat exchanger includes a flue gas pipeline and a CO2 gas pipeline. Each of the flue gas pipeline and the CO2 gas pipeline consists of multiple annular pipes, an inlet manifold, and an outlet manifold. The annular pipes are elongated microchannels. The multiple annular pipes of the flue gas pipeline and the multiple annular pipes of the CO2 gas pipeline are staggered and stacked. The flue gas inlet of the flue gas pipeline is connected to the high-temperature flue gas from the ship's engine or boiler, and the flue gas outlet of the flue gas pipeline is connected to the flue gas inlet of the flue gas pretreatment unit. The CO2 gas inlet of the CO2 gas pipeline is aligned with the cooling zone of the zeolite rotor, and the CO2 gas outlet of the CO2 gas pipeline is aligned with the desorption zone of the zeolite rotor. The flue gas pretreatment unit and the induced draft fan are arranged sequentially behind the zeolite rotor; the flue gas outlet of the flue gas pretreatment unit is aligned with the air inlet of the induced draft fan, and the air outlet of the induced draft fan is aligned with the adsorption zone of the zeolite rotor. The CO2 distributor is located behind the zeolite rotor, and the CO2 distributor has one high-temperature CO2 gas inlet and two high-temperature CO2 gas outlets; the high-temperature CO2 gas inlet is aligned with the desorption zone of the zeolite rotor. The seawater cooler is located behind the zeolite rotor. The inlet of the seawater cooler is connected to a high-temperature CO2 gas outlet of the CO2 distributor, and the outlet of the seawater cooler is aligned with the cooling zone of the zeolite rotor. The CO2 gas inlet of the CO2 liquefaction unit is connected to another high-temperature CO2 gas outlet of the CO2 distributor; The cryogenic CO2 liquid storage tank is connected to the CO2 liquid outlet of the CO2 liquefaction unit.

2. The CO2 capture system for ship fuel flue gas according to claim 1, characterized in that, The flue gas pretreatment unit includes a flue gas pretreatment spray layer, an absorbent spray layer, and a water washing spray layer.

3. The CO2 capture system for ship fuel flue gas according to claim 1, characterized in that, The CO2 liquefaction unit is a thermoacoustic refrigeration machine and includes a thermoacoustic engine, a low-temperature heat exchanger, a high-temperature heat exchanger, and a regenerator connected between the low-temperature heat exchanger and the high-temperature heat exchanger. The thermoacoustic engine generates sound waves by being powered by high-temperature flue gas from a ship engine or boiler. The high-temperature flue gas enters the flue gas inlet of the flue gas pretreatment unit after passing through the thermoacoustic engine. The low-temperature heat exchanger receives the heat work converted from the sound waves, and the CO2 gas inlet of the low-temperature heat exchanger is connected to another high-temperature CO2 gas outlet of the CO2 distributor.

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