System and process for eliminating methane pollution in exhaust gas of LNG-powered ships based on catalyst atomization

Abstract

The present invention discloses a system and process for eliminating methane pollution in the exhaust gas of LNG-powered ships based on catalyst atomization. The system includes a chimney, a water vapor absorption module, a methane reactor, a ball mill module, a catalyst atomization module, and an air supply module. The methane reactor includes a reaction chamber and a heating chamber. The inlet and outlet of the catalyst atomization module are connected to the ball mill module and the reaction chamber via pipelines, respectively, for uniformly atomizing the methane combustion catalyst crushed by the ball mill module into a mist state. The inlet and outlet of the water vapor absorption module are connected to the top of the chimney and the reaction chamber of the methane reactor via pipelines, respectively. The air supply module is connected to the reaction chamber via pipelines for providing balancing gas and combustion-supporting gas to the reaction chamber. The inlet and outlet of the methane reactor's heating chamber are connected to the middle and bottom of the chimney via a heating pipe and a return air pipe, respectively. Through catalyst atomization and chimney heat recycling, methane pollution in the exhaust gas of LNG ships can be eliminated at low cost and with low energy consumption.

Description

Technical Field

[0001] The present invention belongs to the technical field of ship exhaust gas treatment, and in particular relates to a system and process for eliminating methane pollution in exhaust gas of LNG-powered ships based on catalyst atomization. Background Art

[0002] During the fuel combustion process, LNG ships may release incompletely burned methane (CH4) in their exhaust, posing a significant threat to global climate change. As a potent greenhouse gas, methane has a global warming potential (GWP) 84-87 times that of CO2 over a 20-year timeframe, and 28-36 times over a 100-year timeframe. If LNG-powered ships fail to achieve efficient combustion, the methane concentration in their exhaust could reach as high as 0.2% to 5%.

[0003] Methane is the most stable hydrocarbon. A nonpolar molecule with a tetrahedral structure, it is highly stable, with an ignition point of 537°C in air. Currently, the primary methods for treating methane in ship exhaust are high-temperature post-combustion and methane catalytic combustion. Due to methane's stability, high-temperature post-combustion methods, such as plasma generators and electronically controlled post-combustion, require significant energy to achieve complete combustion. Furthermore, limited onboard resources make it difficult to afford the high costs associated with increased energy and system complexity.

[0004] While methane combustion catalysts can lower the reaction temperature, their activity is affected by water content, creating a risk of water toxicity and catalyst loss. Furthermore, methane combustion reactions often utilize fixed-bed reactors, which have low gas-solid reaction efficiency. Fixed-bed reactors also occupy a large area and often require an external heat source, making them difficult to apply to ship environments with limited resources and space. Summary of the Invention

[0005] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and provide a system and process for eliminating methane pollution in the exhaust gas of LNG-powered ships based on catalyst atomization, so as to effectively reduce the emission of methane in the exhaust gas of LNG-powered ships at low cost and low energy consumption.

[0006] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0007] The first aspect of the present invention is to provide a system for eliminating methane pollution in the exhaust gas of LNG-powered ships based on catalyst atomization, comprising a chimney, a water vapor absorption module, a methane reactor, a ball mill module, a catalyst atomization module and an air supply module, wherein:

[0008] The methane reactor comprises a reaction inner chamber and a heating outer chamber;

[0009] The inlet and outlet of the catalyst atomization module are connected to the ball mill module and the reaction cavity through pipelines, respectively, and are used to uniformly atomize the methane combustion catalyst crushed by the ball mill module into a mist state;

[0010] The inlet and outlet of the water vapor absorption module are connected to the top of the chimney and the reaction cavity of the methane reactor respectively through pipelines;

[0011] The gas supply module is connected to the reaction cavity through a pipeline and is used to provide balance gas and combustion-supporting gas to the reaction cavity;

[0012] The inlet and the outlet of the heating outer cavity of the methane reactor are communicated with the middle bottom of the chimney through a heating pipe and a return air pipe respectively.

[0013] According to the present invention, the catalyst atomization module adopts a solid powder atomization device, specifically a combination of one or more of a centrifugal atomization device, an air flow atomization device, and a pressure nozzle atomization device;

[0014] The ball mill module adopts a planetary ball mill to grind the methane combustion catalyst into micron size.

[0015] According to the present invention, a temperature sensor is provided in the reaction cavity of the methane reactor to monitor the actual temperature of the reaction cavity;

[0016] Several temperature sensors are arranged longitudinally in the chimney to monitor the temperature distribution inside the chimney;

[0017] Temperature sensors are also installed on the heating pipes and return air pipes.

[0018] According to the present invention, two sets of fixed rails are provided in the chimney; the parts of the heating pipe and the return air pipe inside the chimney are both liftable pipe sections, which are slidably installed on the two sets of fixed rails respectively, and each is connected to a power mechanism that drives it to move up and down along the rails.

[0019] According to the present invention, a water vapor concentration sensor and a control valve are further installed on the pipeline between the water vapor absorption module and the methane reactor, and the water vapor concentration sensor and the control valve are connected to the inlet of the water vapor absorption module through a first reflux pipeline;

[0020] The water vapor absorption module is filled with a solid desiccant, specifically an anhydrous copper sulfate solid desiccant or a color-changing silica gel mixed with silicic acid gel and cobalt chloride.

[0021] According to the present invention, a methane concentration sensor and a control valve are also installed on the outlet pipeline of the reaction cavity of the methane reactor to monitor the methane content in the outlet exhaust gas; the methane concentration sensor and the control valve are connected to the inlet of the reaction cavity through a second reflux pipeline.

[0022] According to the present invention, the system further comprises a carbon dioxide absorption module connected to the outlet of the reaction cavity. The carbon dioxide absorption module is filled with zeolite powder for adsorbing carbon dioxide and a small amount of methane.

[0023] A second aspect of the present invention is to provide a process for eliminating methane pollution in exhaust gas from LNG-powered ships based on catalyst atomization, comprising the following steps:

[0024] Step 1: The tail gas at the top of the chimney is passed through a pipeline into a water vapor absorption module to remove the water vapor component in the tail gas to reduce the water toxicity of the catalyst, and then passed into the reaction cavity of the methane reactor;

[0025] Step 2: After the methane combustion catalyst is crushed to micron level in the ball mill module, it is sent to the catalyst atomization module, where the solid catalyst powder is evenly atomized into a mist state, and then introduced into the reaction cavity of the methane reactor;

[0026] Step 3: The balance gas and the combustion-supporting gas are introduced into the reaction chamber of the methane reactor from the gas supply module. In the reaction chamber, the dehydrated tail gas, the mist catalyst, the balance gas and the combustion-supporting gas are mixed in a gaseous state;

[0027] Step 4: The high-temperature exhaust gas drawn from the bottom of the chimney is passed into the heated outer chamber of the methane reactor, heating the reaction chamber to reach the reaction temperature, and then returning to the inside of the chimney through the return air pipe; in the reaction chamber, the methane in the exhaust gas undergoes a catalytic combustion reaction to achieve methane removal.

[0028] According to the present invention, in step 2, the methane combustion catalyst is selected from one or more of cobalt-type, aluminum-type, zirconium-type, and platinum-type methane combustion catalysts;

[0029] In step 3, the balance gas is nitrogen, the supporting gas is oxygen, and the volume ratio of nitrogen to oxygen is 3:1~5:1.

[0030] According to the present invention, in step 4:

[0031] The reaction temperature is 250℃~400℃;

[0032] When the temperature of the reaction chamber is higher than the reaction temperature, the air intake position of the heating pipe inside the chimney moves upward to reduce the heating temperature of the heating outer chamber; when the temperature of the reaction chamber is lower than the reaction temperature, the air intake position of the heating pipe inside the chimney moves downward to increase the heating temperature of the heating outer chamber;

[0033] When the exhaust gas temperature in the return air duct is low, the exhaust position of the return air duct inside the chimney moves upward to the area with lower temperature; when the exhaust gas temperature in the return air duct is high, the exhaust position of the return air duct inside the chimney moves downward to the area with higher temperature to maintain the temperature gradient in the chimney.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The system of the present invention achieves gaseous mixing of exhaust gas and atomized catalyst by dehydrating exhaust gas and atomizing catalyst. Compared with traditional fixed-bed reactors, it greatly reduces catalyst loss, increases the effective contact area, reduces the activation energy required for the combustion reaction and the methane combustion temperature, and improves the reaction rate and methane conversion rate.

[0036] (2) Based on the catalyst atomization to reduce the methane combustion temperature, the present invention utilizes the high-temperature exhaust gas inside the chimney to heat the methane combustion reaction without the need for additional heat energy supply, thus realizing the recycling of heat energy and being more suitable for ship environments with limited resources and space.

[0037] (3) The present invention eliminates methane pollution from LNG ship exhaust gas at low cost and low energy consumption, and reduces carbon dioxide emissions, meeting the requirements of green environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the system for eliminating methane pollution in exhaust gas of LNG-powered ships based on catalyst atomization of the present invention.

[0039] In the picture:

[0040] 10-Chimney; 20-Water vapor absorption module; 21-Water vapor concentration sensor and control valve; 22-First reflux pipeline; 30-Methane reactor; 31-Reaction inner chamber; 32-Heating outer chamber; 33-Methane concentration sensor and control valve; 34-Second reflux pipeline; 35-Heating pipeline; 36-Return air pipeline; 40-Ball milling module; 50-Catalyst atomization module; 60-Air supply module; 70-Carbon dioxide absorption module. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. In the description of this application, "first" and "second" are only used to distinguish technical features, rather than to describe a specific sequence. Materials or equipment used in the embodiments that do not indicate the manufacturer are all conventional products that can be purchased through commercial channels.

[0042] Example 1: A system for eliminating methane pollution from LNG-powered ship exhaust gas based on catalyst atomization

[0043] like Figure 1As shown, the system for eliminating methane pollution in exhaust gas of LNG-powered ships based on catalyst atomization of the present invention includes a chimney 10, a water vapor absorption module 20, a methane reactor 30, a ball mill module 40, a catalyst atomization module 50 and an air supply module 60, wherein:

[0044] The methane reactor 30 includes a reaction inner chamber 31 and a heating outer chamber 32;

[0045] The inlet and outlet of the catalyst atomization module 50 are connected to the ball mill module 40 and the reaction chamber 31 through pipelines, respectively, for uniformly atomizing the methane combustion catalyst crushed by the ball mill module 40 into a mist state, and the misted catalyst enters the methane reactor 30 to participate in the reaction;

[0046] The inlet and outlet of the water vapor absorption module 20 are connected to the top of the chimney 10 and the reaction chamber 31 of the methane reactor 30 through pipelines, respectively. After the exhaust gas discharged from the top of the chimney 10 is dehydrated by the water vapor absorption module 20, it enters the reaction chamber 31 for catalytic combustion, effectively reducing the risk of catalyst water poisoning;

[0047] The gas supply module 60 is connected to the reaction chamber 31 through a pipeline, and is used to provide balancing gas and combustion-supporting gas to the reaction chamber 31;

[0048] The inlet and outlet of the heating outer chamber 32 of the methane reactor 30 are connected to the middle and bottom of the chimney 10 through the heating pipe 35 and the return air pipe 36 respectively. The high-temperature exhaust gas drawn out from the middle and bottom of the chimney 10 enters the heating outer chamber 32 to provide heat for the methane combustion reaction, and is then transported back to the chimney 10.

[0049] The catalyst atomization module 50 adopts a solid powder atomization device, specifically a combination of one or more of a centrifugal atomization device, an air flow atomization device, and a pressure nozzle atomization device, preferably a centrifugal atomization device;

[0050] The ball mill module 40 uses a planetary ball mill to grind the methane combustion catalyst into micron size. The particle size of conventional methane combustion catalyst is millimeter size, while the solid powder atomization equipment is mainly used to achieve 80-300μm (median diameter D 50 Therefore, a ball milling module 40 is required to convert millimeter-sized solid particles into micron-sized particles. The output fineness of the planetary ball mill is 1-100 μm.

[0051] The methane combustion catalyst enters the methane reactor 30 after ball milling and atomization, which reduces the problem of uneven catalyst dispersion in the reactor and greatly reduces material loss. At the same time, it greatly increases the exposed area of ​​the catalyst active sites and improves the effective collision frequency between the reactant molecules and the catalyst. The surface of the atomized catalyst is quickly renewed, which can maintain high reaction activity, reduce catalyst surface passivation, avoid the rate drop of the reactants due to diffusion limitation, effectively reduce the combustion temperature of methane, and improve the methane conversion efficiency.

[0052] A temperature sensor is provided in the reaction cavity 31 of the above-mentioned methane reactor 30 for monitoring the actual temperature of the reaction cavity 31; the exhaust gas temperature at the bottom of the above-mentioned chimney 10 is approximately 400°C~500°C, and the temperature at the top is approximately 100°C~200°C. Several temperature sensors (not shown in the figure) are provided in its longitudinal direction for better monitoring the temperature distribution in the chimney 10; temperature sensors (not shown in the figure) are also provided on the above-mentioned heating pipe 35 and return air pipe 36.

[0053] In addition, two sets of fixed rails are provided in the chimney 10 (not shown in the figure); the portions of the heating pipe 35 and the return air pipe 36 inside the chimney 10 are both liftable pipe sections, which are slidably mounted on the two sets of fixed rails, respectively, and are each connected to a power mechanism (not shown in the figure) that drives them to move up and down along the fixed rails.

[0054] By controlling the power mechanism, the height of the air intake position of the heating pipe 35 in the chimney 10 can be adjusted to extract exhaust gas from different temperature areas in the chimney 10 according to heating demand.

[0055] By controlling the power mechanism, the height of the return air duct 36 at the exhaust point within the chimney 10 can be adjusted. Specifically, the height of the exhaust point is adjusted based on the return air temperature detected by a temperature sensor installed on the return air duct 36, thereby controlling the return air to be discharged into a suitable temperature range within the chimney 10. For example, when the return air temperature is too low, the exhaust point is raised to the upper, lower temperature area of ​​the chimney 10; when the return air temperature is high, the exhaust point is lowered to the lower, higher temperature area of ​​the chimney 10, thereby reducing heat loss and maintaining the temperature gradient in the chimney 10.

[0056] like Figure 1 As shown, a water vapor concentration sensor and a control valve 21 are also installed on the pipeline between the water vapor absorption module 20 and the methane reactor 30. The water vapor concentration sensor and the control valve 21 are connected to the inlet of the water vapor absorption module 20 through the first reflux pipeline 22; the water vapor concentration sensor and the control valve 21 are used to monitor the water content in the exhaust gas. When the water content is too high, the exhaust gas is refluxed and re-enters the water vapor absorption module 20 to remove moisture until the requirements are met (water content <10ppm).

[0057] The water vapor absorption module 20 is filled with a desiccant, preferably a solid desiccant, such as anhydrous copper sulfate or a color-changing silica gel mixture of silicic acid gel and cobalt chloride. Liquid desiccant is avoided to reduce the exhaust temperature, thereby reducing the degree and duration of subsequent heating in the methane reactor 30. Furthermore, the solid desiccant selected in this application can be dehydrated and regenerated after adsorption saturation for recycling.

[0058] A methane concentration sensor and a control valve 33 are installed on the outlet pipe of the reaction chamber 31 of the methane reactor 30. The methane concentration sensor and the control valve 33 are connected to the inlet of the reaction chamber 31 through a second reflux pipe 34. The methane concentration sensor and the control valve 33 are used to monitor the methane content in the exhaust gas at the outlet of the reaction chamber 31. When the methane content is too high, the exhaust gas is recirculated into the reaction chamber 31 to remove methane until the methane concentration in the exhaust gas is lower than the methane emission limit for the corresponding ship type in the "Emission Limits and Measurement Methods of Exhaust Pollutants from Ship Engines (China Phase I and II)".

[0059] The above system also includes a carbon dioxide absorption module 70 connected to the outlet of the reaction cavity 31, which is used to remove carbon dioxide from the exhaust gas to reduce the concentration of greenhouse gases. The module is filled with zeolite powder. Compared with the traditional method of removing carbon dioxide through chemical reactions and consuming large amounts of calcium oxide and magnesium oxide, zeolite powder is a natural aluminosilicate with nano-scale pores and a network structure. It captures carbon dioxide through physical adsorption and has the advantages of high adsorption efficiency, good regeneration performance, no chemical changes, and easy regeneration. Its regenerative property after adsorption saturation can greatly reduce consumption costs and is more suitable for use on ships. In addition, zeolite powder has the ability to adsorb a small amount of methane, which can further remove methane.

[0060] Example 2: A process for eliminating methane pollution from LNG-powered ship exhaust gas based on catalyst atomization

[0061] The process of eliminating methane pollution in the tail gas of LNG-powered ships based on catalyst atomization in this embodiment adopts the system of Example 1, including the following steps:

[0062] Step 1: The tail gas (containing methane, water vapor, carbon dioxide, etc.) at the top of the chimney 10 is passed through a pipeline into the water vapor absorption module 20 to remove the water vapor component in the tail gas, and then passed into the reaction cavity 31 of the methane reactor 30;

[0063] Step 2: After the methane combustion catalyst is crushed to micron level by the ball mill module 40, it is sent to the catalyst atomization module 50, where the solid catalyst powder is uniformly atomized into a mist state, and then introduced into the reaction cavity 31 of the methane reactor 30;

[0064] Step 3: The balance gas and the combustion-supporting gas are introduced into the reaction chamber 31 of the methane reactor 30 from the gas supply module 60. In the reaction chamber 31, the dehydrated tail gas, the atomized catalyst, the balance gas and the combustion-supporting gas are mixed in a gaseous state.

[0065] Step 4: The high-temperature exhaust gas drawn from the bottom of the chimney 10 is passed through the heating pipe 35 into the heating outer chamber 32 of the methane reactor 30, heating the reaction chamber 31 to the reaction temperature, and then returns to the interior of the chimney 10 through the return pipe 36. In the reaction chamber 31, the methane in the exhaust gas undergoes a catalytic combustion reaction, thereby removing the methane.

[0066] Step 5: The tail gas after methane removal enters the carbon dioxide absorption module 70 to remove carbon dioxide and a small amount of methane.

[0067] In step 2, the methane combustion catalyst is selected from one or more of cobalt-type, aluminum-type, zirconium-type, and platinum-type methane combustion catalysts; preferably, it is a zirconium-type methane combustion catalyst, such as ZrO2 / Al2O3, CuO / ZrO2, CeO2-ZrO2 and other supported catalysts, and the above catalysts can be purchased through commercial channels.

[0068] In step 3, the balance gas is nitrogen, the supporting gas is oxygen, and the volume ratio of nitrogen to oxygen is 3:1~5:1.

[0069] In step 4, the reaction temperature is 250°C to 400°C, preferably 350°C.

[0070] When the temperature of the reaction chamber 31 is higher than the reaction temperature, the heat supply pipe 35 moves upward at the air intake position inside the chimney 10 to reduce the heating temperature of the heating outer chamber 32; when the temperature of the reaction chamber 31 is lower than the reaction temperature, the heat supply pipe 35 moves downward at the air intake position inside the chimney 10 to increase the heating temperature of the heating outer chamber 32.

[0071] When the exhaust gas temperature in the return air duct 36 is relatively low, the exhaust position of the return air duct 36 inside the chimney 10 moves upward to an area with a lower temperature; when the exhaust gas temperature in the return air duct 36 is relatively high, the exhaust position of the return air duct 36 inside the chimney 10 moves downward to an area with a higher temperature to maintain the temperature gradient in the chimney 10.

[0072] Example 3: Simulation Verification

[0073] The above system was experimentally simulated and verified using a 1m vertical tubular furnace to simulate a chimney. The gas in the chimney was mixed with carbon dioxide, water vapor and methane in a certain proportion to simulate the exhaust gas in an actual chimney (gas was supplied by multiple gas cylinders, and the flow rate of each gas cylinder was adjusted to compound the gas required for the experiment). The mixed gas was first passed through a heating system to simulate the temperature of the chimney exhaust gas (the heating system used a horizontal tubular furnace. The mixed gas was passed into the horizontal tubular furnace and heated to a certain temperature before entering the vertical tubular furnace to start the experiment).

[0074] During the simulation stage, the gas supply flow rate is small, far lower than the actual chimney exhaust gas flow rate, and the drawn-out gas cannot heat the reaction cavity to the required temperature. Therefore, an auxiliary heating device is designed outside the methane reactor to ensure that the required temperature can be reached.

[0075] The water vapor absorption module is filled with anhydrous copper sulfate, the carbon dioxide absorption module is filled with zeolite powder, the ball mill module adopts a planetary ball mill, and the catalyst atomization module adopts a centrifugal solid powder atomization equipment.

[0076] The following tests were conducted on the treatment effects of different methane combustion catalyst types and catalyst treatment methods. The specific parameter conditions and effects are shown in Table 1 below, where:

[0077] Example 1 uses a zirconium-based catalyst, which is ball-milled and atomized before participating in the reaction.

[0078] Example 2 uses a palladium catalyst, which is ball-milled and atomized before participating in the reaction.

[0079] Comparative Example 1 uses a zirconium-based catalyst, which participates in the reaction after being atomized;

[0080] Comparative Example 2 uses a zirconium-based catalyst, which is horizontally stacked in the methane reactor in the form of multi-layer monomer modules and fixed by a supporting grid to form a continuous catalytic bed. That is, the methane reactor in Comparative Example 2 is a traditional fixed-bed reactor.

[0081] Table 1

[0082]

[0083] Comparison of the results of Examples 1-2 and Comparative Examples 1-2 in Table 1 above shows that, when the methane combustion catalyst is subjected to ball milling and atomization and then participates in the methane combustion reaction, methane removal can be efficiently removed at a relatively low reaction temperature. Comparison of Example 1 and Comparative Example 2 shows that, when the same methane combustion catalyst is subjected to ball milling and atomization and then participates in the reaction in a mist state, the methane removal efficiency is increased by 30% compared to a conventional catalytic bed. Comparison of the treatment results of Examples 1-2 and Comparative Example 1 shows that the methane combustion catalyst of the present invention is preferably a zirconium-based catalyst, and the catalyst has better atomization effect and higher reaction activity after ball milling.

[0084] In addition, due to the limited conditions during the simulation experiment (the simulated exhaust gas flow rate is too small), it is necessary to design auxiliary heating equipment. However, it can be seen from Example 1 and Example 2 in Table 1 above that after the catalyst is ball-milled and atomized, when it participates in the methane combustion reaction in a mist state, the reaction temperature can be reduced to 357°C. The exhaust gas temperature at the bottom of the actual ship chimney is about 400°C to 500°C and the flow rate is sufficient. It is entirely possible to rely solely on the exhaust gas energy recycling to heat the reaction cavity to the reaction temperature.

[0085] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the art who, within the technical scope disclosed in the present invention, makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A system for eliminating methane pollution in exhaust gas from LNG-powered ships based on catalyst atomization, characterized in that: It includes a chimney, a water vapor absorption module, a methane reactor, a ball mill module, a catalyst atomization module and a gas supply module, wherein: The methane reactor comprises a reaction inner cavity and a heating outer cavity; The inlet and outlet of the catalyst atomization module are connected to the ball milling module and the reaction cavity through pipelines, respectively, for uniformly atomizing the methane combustion catalyst crushed by the ball milling module into a mist state; The inlet and outlet of the water vapor absorption module are connected to the top of the chimney and the reaction cavity of the methane reactor through pipelines respectively; The gas supply module is connected to the reaction cavity through a pipeline, and is used to provide balance gas and combustion-supporting gas to the reaction cavity; The inlet and the outlet of the heating outer cavity of the methane reactor are communicated with the middle bottom of the chimney through a heating pipe and a return air pipe respectively.

2. The system for eliminating methane pollution in exhaust gas of LNG-powered ships based on catalyst atomization according to claim 1 is characterized in that: The catalyst atomization module adopts solid powder atomization equipment, specifically one or more combinations of centrifugal atomization equipment, air flow atomization equipment, and pressure nozzle atomization equipment; The ball milling module adopts a planetary ball mill, which is used to grind the methane combustion catalyst into micron size.

3. The system for eliminating methane pollution in exhaust gas of LNG-powered ships based on catalyst atomization according to claim 1 is characterized in that: A temperature sensor is provided in the reaction cavity of the methane reactor for monitoring the actual temperature of the reaction cavity; A plurality of temperature sensors are provided in the chimney in the longitudinal direction for monitoring the temperature distribution in the chimney; The heating pipe and the return air pipe are also provided with temperature sensors.

4. The system for eliminating methane pollution in exhaust gas of LNG-powered ships based on catalyst atomization according to claim 1 is characterized in that: Two sets of fixed tracks are provided in the chimney; the parts of the heating pipe and the return air pipe inside the chimney are liftable pipe sections, which are slidably installed on the two sets of fixed tracks and are each connected to a power mechanism that drives it to move up and down along the track.

5. The system for eliminating methane pollution in exhaust gas of LNG-powered ships based on catalyst atomization according to claim 1 is characterized in that: A water vapor concentration sensor and a control valve are also installed on the pipeline between the water vapor absorption module and the methane reactor, and the water vapor concentration sensor and the control valve are connected to the inlet of the water vapor absorption module through a first reflux pipeline; The water vapor absorption module is filled with a solid desiccant, specifically an anhydrous copper sulfate solid desiccant or a color-changing silica gel mixed with silicic acid gel and cobalt chloride.

6. The system for eliminating methane pollution in exhaust gas of LNG-powered ships based on catalyst atomization according to claim 1 is characterized in that: A methane concentration sensor and a control valve are also installed on the outlet pipeline of the reaction cavity of the methane reactor to monitor the methane content in the outlet tail gas; the methane concentration sensor and the control valve are connected to the inlet of the reaction cavity through a second reflux pipeline.

7. The system for eliminating methane pollution in exhaust gas of LNG-powered ships based on catalyst atomization according to claim 1 is characterized in that: The system further comprises a carbon dioxide absorption module connected to the outlet of the reaction cavity. The carbon dioxide absorption module is filled with zeolite powder for adsorbing carbon dioxide and a small amount of methane.

8. A process for eliminating methane pollution in LNG-powered ship exhaust gas based on catalyst atomization, characterized in that: The system for eliminating methane pollution in exhaust gas of LNG-powered ships based on catalyst atomization according to any one of claims 1 to 7 comprises the following steps: Step 1: The tail gas at the top of the chimney is passed through a pipeline into a water vapor absorption module to remove water vapor components in the tail gas to reduce the water toxicity of the catalyst, and then passed into the reaction cavity of the methane reactor; Step 2: After the methane combustion catalyst is crushed to micron level in the ball mill module, it is sent to the catalyst atomization module, where the solid catalyst powder is evenly atomized into a mist state, and then introduced into the reaction cavity of the methane reactor; Step 3: The gas supply module introduces the balance gas and the combustion-supporting gas into the reaction cavity of the methane reactor, and in the reaction cavity, the dehydrated tail gas, the mist catalyst, the balance gas and the combustion-supporting gas are mixed in a gaseous state; Step 4: The high-temperature exhaust gas drawn out from the bottom of the chimney is passed into the heated outer chamber of the methane reactor, heating the reaction chamber to reach the reaction temperature, and then returning to the inside of the chimney through the return gas pipe; in the reaction chamber, the methane in the exhaust gas undergoes a catalytic combustion reaction to achieve methane removal.

9. The process for eliminating methane pollution in LNG-powered ship exhaust gas based on catalyst atomization according to claim 8 is characterized in that: In step 2, the methane combustion catalyst is selected from one or more of cobalt-type, aluminum-type, zirconium-type, and platinum-type methane combustion catalysts; In step 3, the balance gas is nitrogen, the combustion-supporting gas is oxygen, and the volume ratio of nitrogen to oxygen is 3:1 to 5:

1.

10. The process for eliminating methane pollution in LNG-powered ship exhaust gas based on catalyst atomization according to claim 8, characterized in that: In step 4: The reaction temperature is 250°C to 400°C; When the temperature of the reaction chamber is higher than the reaction temperature, the heat supply pipe moves upward at the air intake position inside the chimney to reduce the heating temperature of the heating outer chamber; when the temperature of the reaction chamber is lower than the reaction temperature, the heat supply pipe moves downward at the air intake position inside the chimney to increase the heating temperature of the heating outer chamber; When the exhaust gas temperature in the return air duct is low, the exhaust position of the return air duct inside the chimney moves upward to an area with lower temperature; when the exhaust gas temperature in the return air duct is high, the exhaust position of the return air duct inside the chimney moves downward to an area with higher temperature to maintain the temperature gradient in the chimney.

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