A dry treatment system for marine exhaust gases

Abstract

A kind of ship exhaust gas dry treatment system, to be handled flue gas enters the spent treatment agent storage cabinet through flue gas pipeline, spent treatment agent storage cabinet is connected with desulfurization and decarburization reaction chamber by flue gas pipeline, the flue gas inlet end of desulfurization and decarburization reaction chamber is provided with gas distribution equipment, the rear of gas distribution equipment is provided with reaction space and treatment agent temporary storage space, multiple layers of grid-shaped treatment agent reaction layer are arranged in reaction space, granular treatment agent is laid on treatment agent reaction layer, compressed air is sent to desulfurization and decarburization reaction chamber. Pulse dust removal device and pneumatic conveyor are connected outside desulfurization and decarburization reaction chamber, the granular treatment agent and dust that cannot continue to be recycled in desulfurization and decarburization reaction chamber are sent to desulfurization and decarburization reaction chamber by grinding device, the spent treatment agent formed in desulfurization and dust removal reaction chamber is transported to spent treatment agent storage cabinet by conveying pipeline. The relative position and accumulation mode of treatment agent in space are changed, so as to effectively improve the desulfurization and decarburization efficiency and treatment agent utilization rate.

Description

Technical Field

[0001] This invention belongs to the field of shipbuilding and design, and specifically relates to a treatment system for purifying exhaust gas using a dry method during ship operation. Background Technology

[0002] Commercial vessels commonly use high-powered diesel engines as their main propulsion system. However, to control operating costs, ship operators have consistently used inexpensive, high-sulfur heavy residual oil as fuel. This results in ships emitting large amounts of exhaust gases containing various pollutants such as sulfur oxides (SOx), carbon dioxide (CO2), and particulate matter (PMs), causing serious harm to the atmospheric environment and human health. The International Maritime Organization (IMO) has successively formulated the Annex to the Convention, the "Code for the Prevention of Air Pollution from Ships," and adopted amendments to the "Energy Efficiency Index for Ship Design (EEDI)," imposing strict limits on SOx and CO2 emissions from ships.

[0003] Currently, the main flue gas treatment technology used in ships is wet scrubbing. Although this technology has good desulfurization and decarbonization effects, it consumes a large amount of water during the process, and the scrubbing wastewater is difficult to treat and easily causes serious corrosion to equipment. Currently, ports in many countries, including China, India, Norway, and the United States, have banned the use of open-loop seawater desulfurization systems on ships. Dry flue gas treatment technology uses dry powder or granules as desulfurizing agents to treat pollutants in flue gas. The reaction products are also dry substances. This process has advantages such as system simplicity, low energy consumption, and no secondary pollution. Therefore, this technology has been increasingly used in flue gas treatment in recent years.

[0004] The patent "A Combined Desulfurization and Decarbonization Treatment Device for Ship Exhaust Gas" (CN107349759A) mainly discloses a combined desulfurization and decarbonization treatment device for ship exhaust gas. Although it can efficiently absorb SOx and CO2 from ship exhaust gas by washing with NaOH solution, the pH value of the absorbent in the decarbonization section is not lower than 11.5. The strongly alkaline solution easily corrodes related containers and pipelines, and the treatment of washing waste liquid is very difficult. In addition, the recovery of SOx and CO2 using membrane electrolysis requires a large amount of energy, and the membrane is easily clogged by oil mist and ash substances carried in the washing liquid.

[0005] The patent for a dry desulfurization system for ship exhaust gas (CN110585896A) mainly discloses a dry desulfurization system for ship exhaust gas. Although it can use swirling gas to strip the reaction products on the surface of desulfurizing agent particles, thereby improving the desulfurization effect, it cannot solve the problem of the gas-solid two-phase reaction blind zone. At the same time, the effect of using only swirling gas to blow away the reaction products is limited, and it is difficult to significantly improve the utilization rate of desulfurizing agent.

[0006] While existing dry flue gas treatment technologies can simultaneously remove multiple pollutants such as SOx, CO2, and PMs from flue gas, their treatment efficiency and utilization rate are relatively low. This is particularly true in dry flue gas decarbonization, where the dense product layer on the surface of the treatment agent hinders the full contact and reaction between CO2 molecules and the fresh treatment agent within the product layer. This results in excessively high costs for equipment investment and maintenance, making it particularly unsuitable for carbon capture operations, high sulfur content in flue gas, and fluctuating flue gas temperatures, thus limiting the large-scale commercial application of these technologies. Therefore, effectively improving desulfurization, increasing decarbonization efficiency, and enhancing treatment agent utilization without increasing the dosage is a key issue for promoting the industrial application of dry flue gas treatment. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a dry treatment system for ship exhaust gas, aiming to effectively improve desulfurization and decarbonization without increasing the dosage of treatment agents. The technical solution adopted is as follows:

[0008] A dry exhaust gas treatment system for ships involves the flue gas to be treated sequentially entering a spent gas treatment agent storage tank, a desulfurization and decarbonization reaction chamber, and a desulfurization and dust removal reaction chamber through a flue gas pipeline. After being heated in the spent gas treatment agent storage tank, the gas enters the desulfurization and decarbonization reaction chamber. Spent gas treatment agent refers to desulfurizing agent that is no longer usable or has expired.

[0009] The desulfurization and decarbonization reaction chamber is equipped with gas distribution equipment at its flue gas inlet. Behind the gas distribution equipment are a reaction space and a temporary storage space for the treatment agent. The temporary storage space is located below the reaction space. The reaction space has a cubic structure with multiple horizontally and vertically intersecting grid-like partitions dividing it into multiple cubic reaction chambers. The reaction chambers are lined with granular treatment agent. A pneumatic circulator and a pneumatic conveyor are connected to the outside of the desulfurization and decarbonization reaction chamber, and an air compressor powers the pneumatic circulator and conveyor. The temporary storage space is used to temporarily store granular treatment agent particles with smaller particle sizes that can fall through the gaps in the grid-like partitions after multiple surface replacements.

[0010] A pneumatic conveyor transports the spent treatment agent formed in the desulfurization and decarbonization reaction chamber to the grinding device. After grinding into a powder treatment agent with a fineness of 100-200 mesh, it is sent to the desulfurization and dust removal reaction chamber. The pneumatic conveyor and pneumatic circulator are connected to the spent treatment agent storage tank through flue gas branch pipes. An air compressor is used to provide compressed air, and both the pneumatic circulator and the pneumatic conveyor are driven by compressed air.

[0011] Multiple dust collection bags are fixed inside the desulfurization and dust removal reaction chamber. The waste treatment agent formed in the desulfurization and dust removal reaction chamber is transported to the waste treatment agent storage tank through the conveying pipeline.

[0012] Furthermore, in the aforementioned dry treatment system for ship exhaust gas, multiple transverse grid-type baffles are arranged at equal intervals, and multiple longitudinal grid-type baffles are arranged at equal intervals, with the spacing between adjacent grid-type baffles being 0.5 to 1 mm.

[0013] Furthermore, in the aforementioned dry treatment system for ship exhaust gas, the particulate treatment agent is a porous calcium hydroxide sphere with a particle size of 3-8 mm, and the filling rate of the particulate treatment agent in the reaction space is 85%-95%.

[0014] Furthermore, in the aforementioned dry treatment system for ship exhaust gas, the waste treatment agent storage tank is equipped with a heater, which heats the interior of the waste treatment agent storage tank to 400–550°C.

[0015] Furthermore, in the aforementioned dry treatment system for ship exhaust gas, an ash hopper is installed at the bottom of the desulfurization and dust removal reaction chamber, and the ash hopper is connected to the waste treatment agent storage tank via a conveying pipeline.

[0016] Furthermore, the aforementioned dry exhaust gas treatment system for ships further includes a high-pressure air cylinder group and a low-pressure air cylinder group within the air compressor. The high-pressure air cylinder group is connected to a pneumatic circulator, and the low-pressure air cylinder group is connected to a pneumatic conveyor. The high-pressure air cylinder group stores high-pressure air at a pressure of 1.5–2.0 MPa, which drives the pneumatic circulator in the form of a high-pressure airflow. This utilizes a larger traction force to quickly complete the circulation process and generates a larger airflow impact force, thereby effectively blowing away the powder layer on the surface of the particulate treatment agent.

[0017] Furthermore, in the aforementioned dry treatment system for ship exhaust gas, the pressure of the high-pressure air cylinder group is 1.5–2.0 MPa, and the pressure of the low-pressure air cylinder group is 0.3–0.6 MPa.

[0018] Furthermore, the aforementioned dry treatment system for ship exhaust gas is equipped with a pulse dust collector above the desulfurization and dust removal reaction chamber.

[0019] Furthermore, in the aforementioned dry treatment system for ship exhaust gas, the residence time of the flue gas to be treated in the desulfurization and decarbonization reaction chamber is not less than 2.5 seconds, and the residence time in the desulfurization and dust removal reaction chamber is not less than 1 second.

[0020] Furthermore, in the aforementioned dry treatment system for ship exhaust gas, the waste treatment agent formed in the desulfurization and decarbonization reaction chamber is stored in a temporary storage space.

[0021] The recycling of dry treatment agents is mainly limited by factors such as the surface being covered by a dense product layer and the blockage of particle pores. This invention effectively removes carbonate, sulfite, and sulfate products generated on the surface of the treatment agent by combining rigid collision and surface purging, thus fully exposing the fresh treatment agent inside the product layer. This reduces the negative impact of competitive adsorption of CO2 and SO2, promoting a good situation of efficient recycling and utilization of the treatment agent, and can significantly improve the utilization rate of the treatment agent. When the flue gas residence time in the desulfurization and decarbonization reaction chamber is 2.5s, the utilization rate of the treatment agent can be increased by up to 25%.

[0022] In other methods and processes based on dry flue gas treatment, the treatment agent in the packed tower is generally in a fixed state. Areas with high packing density, good treatment effect, and high back pressure cannot effectively contact the flue gas, creating reaction blind zones. Since the spatial position and packing method cannot be changed, the surface of the treatment agent in these blind zones cannot react with the flue gas, directly affecting desulfurization and decarbonization efficiency. This invention, by circulating and conveying the particulate treatment agent, changes its relative position and packing method in space, allowing the original reaction blind zones to contact the flue gas to be treated, thereby effectively improving desulfurization and decarbonization efficiency. Compared to the traditional packed state, the desulfurization efficiency of the treatment agent in the circulating state can be increased by up to 15%, and the decarbonization efficiency by up to 20%.

[0023] This invention fully utilizes the energy of ship exhaust gas, maintaining the temperature inside the spent fuel tank approximately the same as the flue gas temperature. Based on this, a thermogravimetric method is used to sequentially output high-purity steam, CO2, and SO2. The high-temperature steam can be used for heating ship fuel oil, lubricating oil, and cylinder liner water, while the CO2 can be used to formulate fire extinguishing agents or for liquefied storage. Compared to wet desorption processes, this invention eliminates the need for multi-step lean and rich liquid desorption processes, as well as reboilers and multiple heat exchangers. This significantly reduces initial equipment investment costs, simplifies the recovery process, facilitates crew training and operation, and yields higher purity gaseous products.

[0024] All the equipment in this invention can be arranged on the same floor or in different layers, which can effectively reduce the design and layout difficulty of the ship's engine room and increase the operational correlation and layout flexibility of the corresponding valve groups and pipelines.

[0025] This invention can efficiently remove particulate matter from flue gas while simultaneously removing a small amount of NOx, and can keep the temperature and humidity of the flue gas within a certain controllable range, which facilitates the subsequent installation of SCR systems on ships. It has good integration and scalability. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0027] Among them: 1-exhaust treatment agent storage tank, 2-heating device, 3-desulfurization and decarbonization reaction chamber, 4-pneumatic circulator, 5-pneumatic conveyor, 6-air compressor, 7-treatment agent storage chamber, 8-desulfurization and dust removal reaction chamber, 9-grinding device. Detailed Implementation

[0028] The invention will be further described with reference to the accompanying drawings.

[0029] A dry exhaust gas treatment system for ships includes a spent gas treatment agent storage tank 1 equipped with a heater. The flue gas pipeline to be treated is connected to the inlet of the spent gas treatment agent storage tank, which stores the used spent gas treatment agent. The storage tank is connected to a desulfurization and decarbonization reaction chamber 3 via a flue gas pipeline. The desulfurization and decarbonization reaction chamber is also connected to a treatment agent storage chamber 7, which supplies particulate treatment agent to the desulfurization and decarbonization reaction chamber 3. The desulfurization and decarbonization reaction chamber 3 primarily provides space for the particulate treatment agent to react with the flue gas, removing various pollutants such as SOx and CO2 from the flue gas. A gas distribution device is installed at the flue gas inlet of the desulfurization and decarbonization reaction chamber 3. Behind the gas distribution device are the reaction space and a temporary storage space for the treatment agent. The gas distribution device evenly disperses the flue gas entering the desulfurization and decarbonization reaction chamber into the reaction space. The temporary storage space for the treatment agent is located below the reaction space. The reaction space has a cubic structure and is equipped with multiple horizontally and vertically intersecting grid-like partitions. These partitions divide the reaction space into multiple three-dimensional reaction chambers. The reaction chambers are filled with porous calcium hydroxide spheres with a particle size of 3-8 mm. These porous calcium hydroxide spheres are irregularly shaped spherical particles of the treatment agent. The filling rate of the porous calcium hydroxide spheres in the reaction space is 85%-95%.

[0030] The desulfurization and decarbonization reaction chamber is externally connected to a pneumatic circulator 4 and a pneumatic conveyor 5. An air compressor 6 supplies power to the pneumatic circulator 4 and the pneumatic conveyor 5. The air compressor contains a high-pressure air cylinder group and a low-pressure air cylinder group. The high-pressure air cylinder group is connected to the pneumatic circulator, and the low-pressure air cylinder group is connected to the pneumatic conveyor. The high-pressure air cylinder group stores high-pressure air at a pressure of 1.5–2.0 MPa, driving the pneumatic circulator with a high-pressure airflow. This provides both greater traction force for rapid circulation and a stronger airflow impact force to effectively sweep away the powder layer on the surface of the particulate treatment agent. The low-pressure air cylinder group stores low-pressure air at a pressure of 0.3–0.6 MPa. It only needs to provide a certain traction force to the pneumatic conveyor to stably transport the spent treatment agent to the grinding device.

[0031] During operation, the pneumatic circulator repeatedly pumps the particulate treatment agent from the reaction space. After being extracted from one reaction chamber, the agent is transported to another. In this process, the agent is constantly impacted, its surface is continuously renewed, and its particle size shrinks until it can penetrate multiple layers of partitions to reach the temporary storage space at the bottom. The particulate treatment agent in this temporary storage space is considered "unrecyclable," i.e., depleted treatment agent. The flow of high-pressure air within the reaction space causes the porous calcium hydroxide spheres laid on the treatment agent reaction layer to vibrate. These spheres then collide continuously during the operation of the pneumatic circulator, undergoing partial surface renewal. These multiple collisions effectively break down the carbonate, sulfite, and sulfate products formed on the surface of the particulate treatment agent. Residual dust or ash on the surface is blown away by compressed air, exposing the fresh treatment agent inside the product layer. During the circulation process, the packing pattern of the particulate treatment agent in the corresponding mesh-like reaction layer changes, allowing the previously untreated reaction zone to come into contact with the flue gas to be treated. Simultaneously, high-speed, high-pressure compressed air cuts through the flue gas in a cross-flow manner, forming irregular local gas swirls. This effectively increases the contact area between the flue gas and the particulate treatment agent. After completing the local reaction, the flue gas continues to enter other reaction chambers to repeat the above process. The residence time of the flue gas in the desulfurization and decarbonization reaction chamber is no less than 2.5 seconds, and the residence time in the desulfurization and dust removal reaction chamber is no less than 1 second. During the gas-solid two-phase reaction, the particulate treatment agent is continuously extracted by the pneumatic circulator. During the transport process, it collides with the inner wall of the transport pipeline and completes partial surface renewal. Then, it is pushed by compressed air to the same or different grid spaces, colliding with the particulate treatment agent in that space. Both sides complete partial surface renewal. During the two collisions, the carbonate, sulfite, and sulfate products generated on the surface of the particulate treatment agent can be effectively destroyed. The residual dust or ash on the surface is blown away by the compressed air, allowing the fresh treatment agent inside the product layer to be fully exposed. During the circulation transport process, the stacking mode of the particulate treatment agent in the corresponding grid space changes, allowing the original reaction blind zone to come into contact with the flue gas. At the same time, high-speed, high-pressure compressed air cuts through the flue gas to be treated in a cross-flow state, forming irregular local gas swirls, which can effectively increase the contact area between the flue gas to be treated and the particulate treatment agent. After the flue gas to be treated completes the local reaction, it continues to enter other grid spaces to repeat the above process.

[0032] The pneumatic conveyor 4 transports the treatment agent that cannot be recycled and the dust at the bottom of the desulfurization and decarbonization reaction chamber to the grinding device 9. After being fully ground, the two are formed into a 100-200 mesh powder treatment agent, which is then metered and injected into the flue gas pipeline. The flue gas carries the powder treatment agent into the desulfurization and dust removal reaction chamber 8.

[0033] A pulse dust collector is installed above the desulfurization and dust removal reaction chamber 8. The gas powder treatment agent and flue gas continue to undergo desulfurization reaction in the desulfurization and dust removal reaction chamber 8. At the same time, the dust collector bag effectively filters the powder treatment agent and particulate matter to the outer surface, forming a desulfurization layer of a certain thickness and continuing the desulfurization reaction. When the desulfurization layer fails or the flue gas back pressure increases significantly, the pulse gas is used to blow the attached material on the surface of the dust collector bag into the bottom ash hopper.

[0034] The waste treatment agent in the ash hopper, the bottom of the desulfurization and decarbonization reaction chamber, and the grid space of the desulfurization and decarbonization reaction chamber is transported to the waste treatment agent storage tank 1. The heating device 2 is used to raise the temperature of the inside of the waste treatment agent storage tank to 400°C and 550°C in sequence, and output water vapor and CO2 to the outside respectively. If necessary, the inside of the waste treatment agent storage tank can be heated to 750°C to collect and store SO2 gas.

[0035] This invention fully utilizes the energy of ship exhaust gas, maintaining a temperature approximately the same as the flue gas temperature within the spent fuel tank. Based on this, a thermogravimetric method is used to sequentially output high-purity steam, CO2, and SO2. The high-temperature steam can be used for heating ship fuel oil, lubricating oil, and cylinder liner water, while the CO2 can be used to formulate fire extinguishing agents or for liquefied storage. Compared to wet desorption processes, this invention eliminates the need for multi-step lean and rich liquid desorption processes, as well as reboilers and multiple heat exchangers. This significantly reduces initial equipment investment costs, simplifies the recovery process, facilitates crew training and operation, and yields higher-purity gaseous products. Compared to traditional packed systems, the desulfurization efficiency of the fuel in a circulating state can be increased by up to 15%, and the decarbonization efficiency by up to 20%.

Claims

1. A dry treatment system for ship exhaust gas, characterized in that: The flue gas to be treated enters the waste treatment agent storage tank, the desulfurization and decarbonization reaction chamber and the desulfurization and dust removal reaction chamber in sequence through the flue gas pipeline. After being heated in the waste treatment agent storage tank, it enters the desulfurization and decarbonization reaction chamber. The desulfurization and decarbonization reaction chamber is equipped with a gas distribution device inside and at the flue gas inlet end of the desulfurization and decarbonization reaction chamber. Behind the gas distribution device are a reaction space and a temporary storage space for the treatment agent. The temporary storage space for the treatment agent is located below the reaction space. The reaction space is a cubic structure with multiple horizontal and vertical intersecting grid-type partitions inside. The partitions divide the reaction space into multiple cubic reaction chambers. The reaction chamber is lined with granular treatment agent. The desulfurization and decarbonization reaction chamber is connected to a pneumatic circulator and a pneumatic conveyor. An air compressor powers the pneumatic circulator and the pneumatic conveyor. The pneumatic conveyor transports the waste treatment agent formed in the desulfurization and decarbonization reaction chamber to the grinding device. After grinding into a powder treatment agent with a fineness of 100-200 mesh, it is sent to the desulfurization and dust removal reaction chamber. The pneumatic conveyor and the pneumatic circulator are connected to the waste treatment agent storage cabinet through flue gas branch pipes. Multiple dust collection bags are fixed inside the desulfurization and dust removal reaction chamber. The waste treatment agent formed in the desulfurization and dust removal reaction chamber is transported to the waste treatment agent storage tank through the conveying pipeline.

2. The dry treatment system for ship exhaust gas according to claim 1, characterized in that: Multiple horizontal grid-type partitions are set at equal intervals, and multiple vertical grid-type partitions are set at equal intervals, with the spacing between adjacent grid-type partitions being 0.5 to 1 mm.

3. The dry treatment system for ship exhaust gas according to claim 1, characterized in that: The granular treatment agent is a porous calcium hydroxide sphere with a particle size of 3-8 mm, and the filling rate of the granular treatment agent in the reaction space is 85%-95%.

4. The dry treatment system for ship exhaust gas according to claim 1, characterized in that: The waste treatment agent storage tank is equipped with a heater, which heats the inside of the waste treatment agent storage tank to 400-550°C.

5. A dry treatment system for ship exhaust gas according to claim 1, characterized in that: A dust hopper is installed at the bottom of the desulfurization and dust removal reaction chamber, and the dust hopper is connected to the waste treatment agent storage tank through a conveying pipeline.

6. The dry treatment system for ship exhaust gas according to claim 1, characterized in that: The air compressor is equipped with a high-pressure air cylinder group and a low-pressure air cylinder group. The high-pressure air cylinder group is connected to the pneumatic circulator, and the low-pressure air cylinder group is connected to the pneumatic conveyor.

7. A dry treatment system for ship exhaust gas according to claim 6, characterized in that: The pressure of the high-pressure air cylinder group is 1.5 to 2.0 MPa, and the pressure of the low-pressure air cylinder group is 0.3 to 0.6 MPa.

8. A dry treatment system for ship exhaust gas according to claim 1, characterized in that: A pulse dust collector is installed above the desulfurization and dust removal reaction chamber.

9. A dry treatment system for ship exhaust gas according to claim 1, characterized in that: The residence time of the flue gas to be treated in the desulfurization and decarbonization reaction chamber shall not be less than 2.5s, and the residence time in the desulfurization and dust removal reaction chamber shall not be less than 1s.

10. A dry treatment system for ship exhaust gas according to claim 1, characterized in that: The waste treatment agent formed in the desulfurization and decarbonization reaction chamber is stored in the temporary storage space.

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