A marine methanol engine exhaust treatment device

Abstract

This invention relates to the field of exhaust gas purification technology, and discloses a marine methanol engine exhaust gas treatment device, aiming to solve the problems of existing technologies being unable to simultaneously treat multiple pollutants, catalyst susceptibility to sulfur poisoning, and system complexity. The device includes an exhaust pipe, a heater, a sulfide treatment bed (SGB), a selective catalytic reduction (SCR), and a methanol oxidation catalyst (MOC) connected in sequence, and integrates temperature / pressure sensors, valves, a gas analyzer, an FTIR spectrometer, and a DCU control unit. The SGB is used to remove SO₂. x SCR uses methanol as a reducing agent to remove NO. x The MOC is used to oxidize HC, CO, methanol, and formaldehyde. The DCU controls the heater's start and stop based on the SGB input temperature to ensure the reaction temperature. This invention achieves synergistic and efficient removal of multiple pollutants through a specific sequence of integration, effectively preventing catalyst sulfur poisoning, and simplifies the system by replacing urea with methanol, reducing costs and significantly improving exhaust gas purification efficiency under all operating conditions.

Description

Technical Field

[0001] This invention relates to the field of exhaust gas purification technology, and in particular to an exhaust gas treatment device for marine methanol engines. Background Technology

[0002] Methanol, as a widely available and clean-burning liquid fuel, is gradually becoming an important alternative to traditional gasoline and diesel, especially in heavy-duty transportation and commercial vehicles. In practical production and daily life, methanol engines have been applied in urban public transportation, logistics trucks, ships, and generator sets. For example, in the shipping industry, methanol engines can be used in ocean-going cargo ships, inland waterway vessels, and ro-ro passenger ships, significantly reducing emissions of sulfur oxides (SOx) and particulate matter (PM), meeting increasingly stringent emission regulations such as the International Maritime Organization (IMO) Tier III. At the same time, as a renewable fuel that can be synthesized from biomass, green hydrogen, and captured CO2, methanol provides a feasible decarbonization path for the shipping industry, contributing to the achievement of goals in the field of marine power.

[0003] However, marine methanol engines face significant challenges in terms of exhaust emissions during practical applications. Unlike traditional gasoline or diesel engines, the exhaust composition of marine methanol engines is more complex.

[0004] First, due to the high latent heat of vaporization of methanol, incomplete combustion is likely to occur under low-temperature cold start and low-load conditions, resulting in a significant increase in emissions of conventional pollutants such as carbon monoxide (CO) and unburned hydrocarbons (HC).

[0005] Secondly, methanol fuel itself and some of its oxidation products will cause the emission of unconventional pollutants, especially methanol (CH3OH) and formaldehyde (HCHO). Formaldehyde has been listed as a carcinogen by the World Health Organization, posing a direct threat to human health and the environment.

[0006] Furthermore, in order to meet the stringent requirements for nitrogen oxides (NOx)... x To meet emission regulations, selective catalytic reduction (SCR) technology is essential; however, traditional SCR technologies mostly use urea solution as a reducing agent, which has many drawbacks: urea solution is prone to crystallization at low temperatures, clogging nozzles and pipes; its injection control system is complex, increasing engine manufacturing costs and potential failure points; in addition, there is a risk of secondary pollution from ammonia leakage.

[0007] More importantly, methanol fuel may contain sulfides or sulfur oxides (SO₄) produced during combustion. xThis can lead to irreversible chemical reactions with the noble metal active sites in SCR and methanol oxidation catalysts (MOCs), causing catalyst "sulfur poisoning" and permanent deactivation. Currently, most exhaust gas aftertreatment solutions are designed for only one or a few pollutants, lacking a synergistic and efficient approach to treating SOx and NOx. x Integrated solutions for multiple pollutants such as HC, CO, CH3OH and HCHO.

[0008] Therefore, those skilled in the art urgently need an exhaust gas treatment solution for marine methanol engines. Summary of the Invention

[0009] The core technical problem solved by this invention is: how to provide an integrated, efficient, and low-cost exhaust gas treatment device for marine methanol engines, which can first efficiently remove sulfur oxides to prevent downstream catalyst poisoning by heating the exhaust gas to optimize reaction conditions, then selectively catalytically reduce nitrogen oxides using methanol as a reducing agent by utilizing the easy availability of methanol in the methanol engine, and finally completely oxidize residual carbon monoxide, hydrocarbons, methanol, formaldehyde and other harmful substances, thereby achieving synergistic purification of multiple conventional and unconventional pollutants.

[0010] Solving this core problem has significant implications for the industry:

[0011] First, this is the key to whether methanol engines can meet increasingly stringent emission regulations. If the problem of multi-pollutant co-processing is not solved, methanol engines will be unable to enter the mainstream market due to non-compliance with emission standards.

[0012] Second, solving this core problem will directly break through the technical bottleneck of promoting marine methanol engines. By solving the problem of catalyst sulfur poisoning and using methanol to replace urea, the complexity of the aftertreatment system and operation and maintenance costs can be greatly reduced, the reliability of the system and user acceptance can be improved, thereby accelerating the commercial application of methanol fuel in the transportation and energy sectors.

[0013] Third, the successful development of this device will provide important technical reference for exhaust gas purification of engines using other alternative fuels (such as ethanol and biodiesel).

[0014] To address the aforementioned core technical problems, this invention designs a marine methanol engine exhaust gas treatment device. Its purpose is to integrate a sulfide treatment bed (SGB), a selective catalytic reduction (SCR), and a methanol oxidation catalyst (MOC) in sequence, supplemented by heaters, sensors, valves, a gas analyzer, and a DCU control unit. Through precise temperature and pressure monitoring and control, it achieves the stepwise and efficient removal of multiple pollutants from the exhaust gas of marine methanol engines.

[0015] To achieve the above objectives, the specific technical solution of the present invention is a marine methanol engine exhaust gas treatment device, comprising:

[0016] Exhaust pipe;

[0017] A heater is connected to the output end of the exhaust pipe;

[0018] A sulfide-treated bed reactor, the input end of which is connected to the output end of the heater;

[0019] A selective catalytic reduction reactor, the input end of which is connected to the output end of the sulfide treatment bed reactor (5);

[0020] A methanol oxidation catalytic reactor, the input of which is connected to the output of the selective catalytic reduction reactor;

[0021] The first temperature sensor is installed at the input end of the sulfide treatment bed reactor;

[0022] The DCU control unit is electrically connected to the heater and the first temperature sensor.

[0023] The DCU control unit is configured to control the start and stop of the heater based on the temperature monitored by the first temperature sensor.

[0024] In at least one embodiment, the sulfide treatment bed reactor, the selective catalytic reduction reactor, and the methanol oxidation catalyst reactor are connected and integrated via flanges in sequence.

[0025] In one or more embodiments, the sulfide-treated bed reactor is used to remove SO2 from engine exhaust gases. x ;

[0026] In one or more embodiments, the selective catalytic reduction reactor is used to remove NO from the exhaust gas using CH3OH as a reducing agent. x ;

[0027] In one or more embodiments, the methanol oxidation catalyst reactor is used to remove HC, CO, CH3OH and HCHO from the exhaust gas.

[0028] In at least one embodiment, the exhaust gas treatment device further includes:

[0029] A second temperature sensor is installed at the output end of the sulfide treatment bed reactor;

[0030] The third temperature sensor is installed at the output end of the selective catalytic reduction reactor.

[0031] In at least one embodiment, the exhaust gas treatment device further includes:

[0032] The first pressure sensor is installed at the input end of the sulfide treatment bed reactor;

[0033] The second pressure sensor is installed at the output end of the methanol oxidation catalyst reactor.

[0034] In at least one embodiment, the exhaust gas treatment device further includes:

[0035] The first valve and the first gas analyzer are installed at the output end of the sulfide treatment bed reactor;

[0036] The second valve and the second gas analyzer are installed at the output end of the selective catalytic reduction reactor;

[0037] The third valve and the Fourier transform infrared spectrometer are installed at the output end of the methanol oxidation catalyst reactor.

[0038] When one or more embodiments are executed, the first valve is used to control the first gas analyzer to analyze the SO₂ content in the gas output from the sulfide treatment bed reactor. x Content monitoring;

[0039] The second valve is used to control the NO content in the gas output from the selective catalytic reduction reactor by the second gas analyzer. x Content monitoring;

[0040] The third valve is used to control the Fourier transform infrared spectrometer to monitor the content of HC, CO, HCHO and CH3OH in the gas output from the methanol oxidation catalyst reactor.

[0041] In at least one embodiment, the DCU control unit is configured as follows:

[0042] When the temperature monitored by the first temperature sensor does not exceed 250°C, the heater is activated to make the temperature of the tail gas entering the sulfide treatment bed reactor higher than 250°C.

[0043] When the temperature monitored by the first temperature sensor exceeds 250°C, the heater is shut down.

[0044] In at least one embodiment, a control method for controlling the exhaust gas treatment device includes the following steps:

[0045] The temperature of the exhaust gas discharged from the engine and flowing through the exhaust pipe is monitored by the first temperature sensor;

[0046] When the monitored temperature does not exceed 250°C, the heater is activated through the DCU control unit to heat the exhaust gas;

[0047] When the monitored temperature exceeds 250°C, the heater is shut down via the DCU control unit.

[0048] The exhaust gas is sequentially passed through the sulfide treatment bed reactor, the selective catalytic reduction reactor, and the methanol oxidation catalyst reactor for treatment.

[0049] In at least one embodiment, the control method further includes an exhaust gas composition monitoring step:

[0050] Open the first valve and use the first gas analyzer to monitor the SO at the output of the sulfide treatment bed reactor. x content;

[0051] Open the second valve and use the second gas analyzer to monitor the NO at the output of the selective catalytic reduction reactor. x content;

[0052] Open the third valve and use the Fourier transform infrared spectrometer (10) to monitor the contents of HC, CO, HCHO and CH3OH at the output of the methanol oxidation catalyst reactor.

[0053] In at least one embodiment, a marine methanol engine exhaust gas purification system includes the exhaust gas treatment device and a methanol engine.

[0054] The exhaust port of the marine methanol engine is connected to the input end of the exhaust pipe. Compared with the prior art, the technical solution disclosed in this application has the following non-obvious technical features:

[0055] First, this application achieves a specific functional sequence integration of "desulfurization first, then reduction, and finally oxidation." Existing technologies mostly study SCR or MOC separately, or simply in series; however, this invention creatively integrates the SGB reactor, SCR reactor, and MOC reactor according to a specific logical sequence of "desulfurization-reduction-oxidation." This sequence is not a simple functional superposition, but rather based on a profound understanding of the characteristics of methanol engine exhaust pollutants and the chemical mechanism of catalysts: first, actively removing SO2 via SGB. x This provides a "clean" environment for downstream SCR and MOC catalysts, fundamentally solving the long-standing technical problem of sulfur poisoning in precious metal catalysts and ensuring the long-term, efficient, and stable operation of the entire system. This multi-level synergistic defensive design targeting the characteristics of methanol engines is something that those skilled in the art would find difficult to conceive of directly under the single aftertreatment technology mindset;

[0056] Second, this application adopts a methanol-SCR technology route of "treating waste with waste". Traditional SCR technology generally uses urea as a reducing agent, which brings problems of cost, complexity and secondary pollution. This invention uses the methanol fuel carried by the methanol engine itself as the reducing agent of the SCR reactor to remove NO from the exhaust gas. x This feature cleverly achieves "waste treatment with waste," that is, using the engine's own fuel to treat the pollutants it produces; this not only eliminates the need for a complex urea injection system and its related costs, but also addresses the issue of NOx emissions. x Simultaneously, it consumes some of the unburned methanol (CH3OH) in the exhaust gas, achieving synergistic reduction among pollutants. This technical approach, which deeply couples the advantages of engine fuel supply with the needs of exhaust aftertreatment, transcends the scope of conventional aftertreatment device design.

[0057] Third, this application employs a closed-loop heating control logic based on multi-sensor feedback. Existing technologies may simply add a heater to the exhaust pipe, while this invention sets temperature sensors at the input and output ends of the SGB reactor and the output end of the SCR reactor, and combines them with pressure sensors to construct a complete monitoring network. In particular, the DCU control unit precisely controls the start and stop of the heater based on the feedback from the SGB input temperature sensor (the first temperature sensor), with 250°C as the threshold. This feature ensures that the exhaust gas can reach the optimal reaction temperature window required by each reactor of SGB, SCR, and MOC under any operating conditions (especially cold start and low load conditions), realizing active and precise intervention in reaction conditions rather than passive response, and significantly improving the purification efficiency under all operating conditions.

[0058] Fourth, this application possesses multi-dimensional and hierarchical pollutant monitoring and assessment capabilities. This invention not only integrates the treatment device but also integrates valves, gas analyzers, and Fourier transform infrared spectrometers (FTIR) at the output ends of the SGB, SCR, and MOC reactors. This system can independently monitor specific pollutants (SO4) after each treatment unit. x NO x The concentration changes of HCl, CO, HCHO, and CH3OH are monitored; this allows the device to not only treat exhaust gas but also evaluate the conversion efficiency of each unit in real time, providing key data support for system optimization, fault diagnosis, and catalyst lifetime prediction. This integrated design, which deeply integrates "treatment" and "diagnosis" functions, reflects a high degree of advancement and non-obviousness.

[0059] Compared with existing technologies, the present invention has the following beneficial effects: 1. The present invention achieves efficient synergistic treatment of multiple pollutants. Through the specific sequential integration of three reactors—SGB, SCR, and MOC—the present invention can simultaneously and efficiently remove sulfur oxides (SO₄) from methanol engine exhaust gas. x), nitrogen oxides (NO) x It can treat carbon monoxide (CO), hydrocarbons (HC), and unconventional pollutants such as methanol (CH3OH) and formaldehyde (HCHO), solving the problem that existing technologies can only treat single or a few pollutants and meeting more stringent emission regulations.

[0060] 2. This invention can effectively prevent catalyst sulfur poisoning and extend system life. By setting an SGB reactor upstream of the SCR and MOC reactors, SO2 in the tail gas is pre-treated. x It is converted into stable sulfate, avoiding contact between precious metal catalysts and sulfur, fundamentally solving the problem of catalyst sulfur poisoning and deactivation, significantly extending the effective working life of the post-treatment system and reducing maintenance costs;

[0061] 3. This invention simplifies the system structure, reduces costs and risks, and uses methanol as the reducing agent in the SCR reactor to replace the traditional urea-SCR system. This eliminates the need for urea tanks, urea pumps, injectors, heating pipes, and complex control systems, simplifying the overall structure of the engine aftertreatment system, reducing manufacturing costs and failure rates, while avoiding the risks of urea crystallization and ammonia leakage, thus improving the reliability and safety of the system.

[0062] 4. This invention improves the purification efficiency under all operating conditions. Through the electrical connection between the DCU control unit and the temperature sensor and heater, closed-loop control of the exhaust gas temperature entering the SGB reactor is achieved. When the exhaust temperature is below 250°C, the heater is activated for preheating, ensuring that each catalytic reaction occurs within its optimal temperature window. This significantly improves the exhaust gas purification efficiency of the engine under low-temperature conditions such as cold starts and low loads. (See attached figures for details.)

[0063] Figure 1 This is a schematic diagram of the structure of the device described in this invention;

[0064] Figure 2 This is a flowchart illustrating the control method described in this invention;

[0065] Figure 1 In the system, 1. Exhaust pipe; 2. Heater; 31. First pressure sensor; 32. Second pressure sensor; 41. First temperature sensor; 42. Second temperature sensor; 43. Third temperature sensor; 5. SGB reactor; 6. SCR reactor; 7. MOC reactor; 81. First valve; 82. Second valve; 83. Third valve; 91. First gas analyzer; 92. Second gas analyzer; 10. Fourier transform infrared spectrometer; 11. DCU control unit; 12. Methanol engine. Detailed Implementation

[0066] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings;

[0067] In this application, a sulfide guard bed (SGB) is a catalytic reactor filled with a specific adsorbent or reactant, specifically designed to selectively capture and remove sulfur oxides (SO₄) from gas streams (such as engine exhaust). x SO₂ is typically converted into stable sulfate compounds; in this application, SGB is the first stage of the entire treatment unit, and its core function is to act as a "protective barrier," pre-treating toxic SO₂ before the exhaust gas enters the expensive SCR and MOC catalysts. x Removal is crucial and a prerequisite for preventing irreversible sulfur poisoning of downstream precious metal catalysts and ensuring the long-term, efficient, and stable operation of the entire post-treatment system.

[0068] A selective catalytic reduction (SCR) device is a catalytic reaction apparatus that, under the action of a catalyst, uses a reducing agent (such as ammonia, urea, or hydrocarbons) to selectively remove nitrogen oxides (NOx) from waste gas. x The methanol is reduced to harmless nitrogen (N2) and water (H2O). In this application, SCR is the second-stage core treatment unit. Its innovation lies in using methanol (CH3OH) carried by the methanol engine itself as a reducing agent. This not only avoids the high cost and complexity of the traditional urea-SCR system, but also consumes a portion of the unburned methanol pollutants in the exhaust gas while treating NOx, achieving synergistic control among pollutants.

[0069] A methanol oxidation catalyst (MOC) is a catalytic device specifically designed to promote the complete oxidation reaction of methanol (CH3OH) and other unburned hydrocarbons (HC) and carbon monoxide (CO) with oxygen at a relatively low temperature, producing carbon dioxide (CO2) and water. In this application, the MOC is the final "fallback" treatment unit. Its function is to completely oxidize the residual HC, CO, CH3OH after the first two stages of treatment, as well as the highly toxic intermediate product formaldehyde (HCHO) produced by the partial oxidation of methanol, ensuring that all harmful pollutants are ultimately converted into harmless CO2 and H2O, thereby achieving complete purification of the exhaust gas.

[0070] A Data Control Unit (DCU) is an electronic control module that typically includes a microprocessor and memory. It receives signals from multiple sensors (such as temperature and pressure sensors), processes and judges them according to preset logic or algorithms, and issues control commands to actuators (such as heaters and valves). In this application, the DCU is the "brain" of the entire device. It receives the temperature signal at the SGB inlet and precisely controls the start and stop of the heater through a preset algorithm (250°C threshold). This achieves active and intelligent closed-loop management of the exhaust gas treatment temperature, ensuring that each reactor operates under optimal conditions, especially under low-temperature conditions such as engine cold start, which greatly improves purification efficiency.

[0071] A heater is a device that converts electrical energy or other forms of energy into heat energy to heat fluids (such as engine exhaust) flowing through it, thereby increasing the fluid's temperature. In this application, the heater is installed before the SGB reactor. Its function is to compensate for the deficiency of methanol engines having excessively low exhaust temperatures during low load or cold start, which do not reach the catalyst activation temperature. Through the control of the DCU, the heater can be activated as needed, quickly raising the exhaust temperature to a high-efficiency reaction window of over 250°C, ensuring that ideal pollutant purification effects can be obtained throughout the entire operating range of the engine.

[0072] refer to Figure 1 This diagram illustrates a schematic structural block diagram of a marine methanol engine exhaust gas treatment device according to one or more embodiments of this application. The device is applied in the field of marine methanol engine exhaust gas purification and treatment, and is used to achieve SO2 purification. x NO x The device is designed for the synergistic and efficient removal of multiple pollutants, including HC, CO, CH3OH and HCHO. It comprises: an exhaust pipe 1, a heater 2, a sulfide treatment bed reactor 5 (hereinafter referred to as SGB reactor 5), a selective catalytic reduction reactor 6 (hereinafter referred to as SCR reactor 6), a methanol oxidation catalyst reactor 7 (hereinafter referred to as MOC reactor 7), a first temperature sensor 41, a DCU control unit 11, and multiple pressure sensors, temperature sensors, valves and analytical instruments.

[0073] exist Figure 1 In at least one embodiment shown, the output end of the exhaust pipe 1 is connected to the input end of the heater 2, the output end of the heater 2 is connected to the input end of the SGB reactor 5, the output end of the SGB reactor 5 is connected to the input end of the SCR reactor 6, and the output end of the SCR reactor 6 is connected to the input end of the MOC reactor 7.

[0074] When one or more embodiments are implemented, the SGB reactor 5, SCR reactor 6 and MOC reactor 7 are connected and integrated in sequence via flanges. Each reactor is a cylindrical body made of stainless steel and is loaded with the corresponding catalyst inside.

[0075] In at least one embodiment, the SGB reactor 5 is filled with a sulfide adsorbent for removing SO2 from engine exhaust. x It is converted into a stable sulfate, thereby eliminating SO. x This is to prevent sulfur poisoning of downstream catalysts.

[0076] In at least one embodiment, the SCR reactor 6 is loaded with an HC-SCR catalyst, used to use methanol (CH3OH) carried by the methanol engine itself as a reducing agent to remove NO from the exhaust gas. x It is catalytically reduced to N2, while consuming some of the CH3OH in the exhaust gas.

[0077] In at least one embodiment, the MOC reactor 7 is loaded with an oxidation catalyst for completely oxidizing HCHO, which is generated from the partial oxidation of residual HC, CO, CH3OH and methanol in the exhaust gas, into CO2 and H2O.

[0078] In at least one embodiment, the device may optionally further include a complete temperature monitoring network;

[0079] Specifically, a first temperature sensor 41 is installed at the input end of the SGB reactor 5 to monitor the exhaust gas temperature before entering the SGB reactor 5, i.e., the original exhaust gas temperature of the engine 12; a second temperature sensor 42 is installed at the output end of the SGB reactor 5 to monitor the exhaust gas temperature after the reaction in the SGB reactor 5, which is also the inlet temperature of the SCR reactor 6. A third temperature sensor 43 is installed at the output end of the SCR reactor 6 to monitor the exhaust gas temperature after the reaction in the SCR reactor 6, which is also the inlet temperature of the MOC reactor 7.

[0080] Additionally, the device also includes a pressure monitoring network;

[0081] The first pressure sensor 31 is installed at the input end of the SGB reactor 5, and the second pressure sensor 32 is installed at the output end of the MOC reactor 7.

[0082] By comparing the readings of the two pressure sensors, the exhaust back pressure of the entire treatment unit can be monitored in real time, ensuring that it meets the engine's limit requirements for exhaust back pressure.

[0083] In at least one embodiment, the DCU control unit 11 is electrically connected to the heater 2 and the first temperature sensor 41; the DCU control unit 11 is configured to control the start and stop of the heater 2 according to the following logic based on the temperature monitored by the first temperature sensor 41:

[0084] First, the DCU control unit 11 reads the temperature value T fed back by the first temperature sensor 41 in real time;

[0085] Then, the temperature value is compared with the preset threshold temperature T0 (T0=250℃ in this embodiment).

[0086] Specifically, when T ≤ 250℃, it indicates that the engine exhaust temperature is too low and cannot meet the activation temperature requirements of SGB, SCR and MOC catalysts. At this time, the DCU control unit 11 sends a start command to the heater 2, and the heater 2 begins to heat the exhaust gas flowing through it until the temperature monitored by the first temperature sensor 41 is higher than 250℃, ensuring that the exhaust gas entering the SGB reactor 5 is in the optimal reaction temperature window.

[0087] When T > 250℃, it indicates that the engine exhaust temperature has reached or exceeded the efficient operating range of the catalyst. At this time, the DCU control unit 11 sends a shutdown command to the heater 2, the heater 2 stops working, and the exhaust gas directly enters the SGB reactor 5 for treatment to save energy.

[0088] In at least one embodiment, in order to ensure the representativeness and accuracy of gas sampling during pollutant monitoring, the operation of valves 81, 82, and 83 needs to follow a specific timing sequence.

[0089] In some embodiments, when exhaust gas composition analysis is required, the DCU control unit 11 first sends a command to open the first valve 81. After the gas flow stabilizes, the first gas analyzer 91 starts and performs SO analysis. x Concentration measurement. After the measurement is completed, close the first valve 81. Similarly, open the second valve 82 in sequence to measure the NOx concentration with the second gas analyzer 92, and open the third valve 83 in sequence to measure the concentrations of HC, CO, HCHO and CH3OH with the Fourier transform infrared spectrometer 10; this time-sequential atomic operation avoids gas cross-interference and ensures the independence of the monitoring data.

[0090] When one or more embodiments are executed, in response to the pressure difference between the first pressure sensor 31 and the second pressure sensor 32 exceeding a preset safety threshold (e.g., exceeding 50 kPa), the DCU control unit 11 determines that the SGB reactor 5 or a subsequent reactor is blocked; at this time, an error handling process is executed, which includes: sending a torque limiting command to the engine control unit to reduce the exhaust flow, illuminating the fault indicator on the instrument panel, and recording the fault log.

[0091] By integrating the three reactors SGB, SCR, and MOC in a specific sequence, and through the coordinated operation of the heater, multiple sensors, and DCU control unit, this device achieves efficient removal of multiple pollutants through a "first desulfurization, then reduction, and finally oxidation" process. This effectively prevents catalyst sulfur poisoning and simplifies the system structure by replacing urea with methanol, significantly improving the exhaust gas purification efficiency and system reliability under all operating conditions.

[0092] refer to Figure 2 This diagram illustrates a schematic flowchart of a control method for controlling the aforementioned marine methanol engine exhaust gas treatment device according to one or more embodiments of this application. The method is applied to the exhaust gas aftertreatment system of the methanol engine 12 and is executed by the DCU control unit 11.

[0093] In at least one embodiment, the DCU control unit 11 monitors the temperature of the exhaust gas discharged from the engine 12 and flowing through the exhaust pipe 1 via the first temperature sensor 41;

[0094] Specifically, the DCU control unit 11 reads the value of the first temperature sensor 41 installed at the input of the SGB reactor 5 in real time at a preset sampling frequency (e.g., 100Hz), which represents the original exhaust temperature of the engine.

[0095] In at least one embodiment, the DCU control unit 11 determines whether the monitored temperature exceeds 250°C;

[0096] When the monitored temperature does not exceed 250°C, the DCU control unit 11 starts the heater 2 to heat the exhaust gas. The heater 2 continues to work until the temperature reported by the first temperature sensor 41 is higher than 250°C.

[0097] When the monitored temperature exceeds 250°C, the DCU control unit 11 shuts down the heater 2.

[0098] In at least one embodiment, the exhaust gas is treated sequentially by passing through the sulfide treatment bed reactor 5, the selective catalytic reduction reactor 6, and the methanol oxidation catalyst reactor 7.

[0099] Optionally, in some embodiments, the control method further includes a pressure monitoring step, wherein during the exhaust gas treatment process, the DCU control unit 11 synchronously reads the values ​​of the first pressure sensor 31 and the second pressure sensor 32, and calculates the pressure difference in real time. .when When the rate of increase continues to exceed a predetermined rate (e.g., 1 kPa / s), it indicates that the system may be at risk of congestion.

[0100] In some embodiments, "heating the exhaust gas" further includes closed-loop control logic;

[0101] Specifically, the DCU control unit 11 uses a PID (proportional-integral-derivative) control algorithm to adjust the heating power of the heater 2;

[0102] First, set the target temperature to 260℃ (slightly higher than the activation temperature to provide a margin).

[0103] Then, based on the real-time feedback value T of the first temperature sensor 41 and the target value... deviation Calculate heater control quantity ;

[0104] Finally, the control output of the PWM (Pulse Width Modulation) signal is configured to a safe state (default shutdown) to prevent the system from going out of control.

[0105] In at least one embodiment, when the control method is unable to obtain valid temperature data due to an open circuit or short circuit fault in the first temperature sensor 41 or the second temperature sensor 42, the DCU control unit 11 executes an error handling process.

[0106] The process includes: immediately shutting off the heater (2), adopting the default safety control mode (i.e., not performing active heating), recording the fault code, and illuminating the engine fault light to prompt the operator to perform maintenance.

[0107] This control method achieves proactive and precise closed-loop management of exhaust gas treatment temperature through the coordinated operation of the above processes, ensuring that the SGB, SCR, and MOC reactors operate under optimal conditions. Especially under low-temperature conditions such as engine cold start, it greatly improves purification efficiency and has comprehensive fault diagnosis and safety protection functions.

[0108] In at least one embodiment, a marine methanol engine exhaust gas purification system includes the methanol engine exhaust gas treatment device and a methanol engine 12; the system is used to realize the complete process from engine power to exhaust gas complete purification.

[0109] In at least one embodiment, the exhaust port of the methanol engine 12 is connected to the input end of the exhaust pipe 1; when the system is running, the high-temperature exhaust gas generated by the methanol engine 12 after burning methanol fuel first enters the exhaust pipe 1 through the exhaust port.

[0110] When one or more embodiments are executed, the core processing module of the entire system consists of three reactors connected in series:

[0111] Primary treatment module (SGB reactor 5): Its input end is connected to exhaust pipe 1 via heater 2; this module is configured to receive engine exhaust gas and capture SO2 using an internal sulfur adsorbent. x This generates stable sulfates and outputs "low-sulfur tail gas";

[0112] Secondary treatment module (SCR reactor 6): Its input is connected to the output of SGB reactor 5. This module is configured to receive "low-sulfur tail gas" and utilize methanol from the methanol engine 12 fuel supply system as an external reducing agent to remove NO from the tail gas. x Selective catalytic reduction to N2 produces "denitrile tail gas";

[0113] The third-stage treatment module (MOC reactor 7) has its input end connected to the output end of the SCR reactor 6. This module is configured to receive the "denitrification tail gas" and use its internal oxidation catalyst to completely oxidize the residual HC, CO, CH3OH, and HCHO in the tail gas into CO2 and H2O, ultimately outputting clean tail gas for emission into the atmosphere.

[0114] In at least one embodiment, the system may optionally include a remote monitoring module electrically connected to the DCU control unit 11; the remote monitoring module receives sensor data (temperature, pressure) and pollutant concentration data measured by gas analyzers 91, 92, and 10 uploaded by the DCU control unit 11 via a CAN bus or wireless communication network (such as 4G / 5G).

[0115] In at least one embodiment, the heating control logic of the system is implemented as follows:

[0116] First, the DCU control unit 11 is initialized and reads the calibration parameters stored therein, including: target start-up temperature. Temperature control dead zone ;

[0117] Then, the DCU control unit 11 periodically reads the value of the first temperature sensor 41. ;

[0118] Next, a judgment is made: if ,Right now Then start heater 2;

[0119] if ,Right now Then shut down heater 2; if If so, the current state of heater 2 remains unchanged;

[0120] Finally, heater 2 executes the DCU's instructions to achieve hysteresis control of the exhaust gas temperature, preventing the heater from frequently starting and stopping near the threshold point.

[0121] In at least one embodiment, in order to ensure the precise supply of methanol as a reducing agent to the SCR reactor 6, the system employs an access control mechanism in the methanol injection control.

[0122] Specifically, before issuing an opening command to the methanol injection valve, the DCU control unit 11 must verify two conditions:

[0123] ① The engine is in a steady state or non-regenerative operating condition;

[0124] ② The SCR outlet temperature monitored by the third temperature sensor 43 is between 180℃ and 450℃;

[0125] The DCU will grant "methanol injection permission" and issue injection pulse width instructions only when both conditions are met simultaneously; if either condition is not met, the injection permission will be locked to prevent methanol injection from causing pollution or waste.

[0126] In at least one embodiment, the system responds to the detection of SO at the output of the SGB reactor 5 by the first gas analyzer 91. x If the concentration exceeds the threshold (e.g., 10 ppm), the system determines that the SGB adsorbent is saturated. At this time, the error handling procedure is executed: the DCU control unit 11 records the "SGB saturation" fault code, reduces the maximum allowable torque of the engine, and prompts the ship to go to the shipyard for maintenance as soon as possible to replace or regenerate the SGB reactor 5.

[0127] This system, through the deep coupling and coordinated operation of the methanol engine 12 and the multi-stage treatment unit, achieves the treatment of SO2 in the methanol engine exhaust gas. x NO x It provides a full-spectrum, high-efficiency synergistic purification of methanol, HC, CO, CH3OH and HCHO, while also possessing intelligent temperature control, remote monitoring and fault self-diagnosis capabilities, providing a reliable aftertreatment solution for the commercial promotion of methanol engines.

[0128] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, the phrase "comprising an element defined as..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0129] The above technical solutions only embody the preferred technical solutions of the present invention. Any modifications that may be made by those skilled in the art to certain parts thereof embody the principles of the present invention and fall within the protection scope of the present invention.

Claims

1. A marine methanol engine exhaust gas treatment device, characterized in that, include: Exhaust pipe (1); The heater (2) is connected to the output end of the exhaust pipe (1); A sulfide treatment bed reactor (5) has its input end connected to the output end of the heater (2); A selective catalytic reduction reactor (6) is connected at its input end to the output end of the sulfide treatment bed reactor (5); The methanol oxidation catalyst reactor (7) has its input end connected to the output end of the selective catalytic reduction reactor (6); The first temperature sensor (41) is installed at the input end of the sulfide treatment bed reactor (5); The DCU control unit (11) is electrically connected to the heater (2) and the first temperature sensor (41); The DCU control unit (11) is configured to control the start and stop of the heater (2) based on the temperature monitored by the first temperature sensor (41).

2. The exhaust gas treatment device according to claim 1, characterized in that, The sulfide treatment bed reactor (5), the selective catalytic reduction reactor (6), and the methanol oxidation catalyst reactor (7) are connected and integrated in sequence via flanges. The sulfide treatment bed reactor (5) is used to eliminate SO x from the engine exhaust gas The selective catalytic reduction reactor (6) is used for eliminating NO in the tail gas with CH3OH as a reducing agent x ; The methanol oxidation catalyst reactor (7) is used to remove HC, CO, CH3OH and HCHO from the exhaust gas.

3. The exhaust gas treatment device according to claim 1, characterized in that, Also includes: The second temperature sensor (42) is installed at the output end of the sulfide treatment bed reactor (5); The third temperature sensor (43) is installed at the output end of the selective catalytic reduction reactor (6).

4. The exhaust gas treatment device according to claim 1, characterized in that, Also includes: The first pressure sensor (31) is installed at the input end of the sulfide treatment bed reactor (5); The second pressure sensor (32) is installed at the output end of the methanol oxidation catalyst reactor (7).

5. The exhaust gas treatment device according to claim 1, characterized in that, Also includes: The first valve (81) and the first gas analyzer (91) are installed at the output end of the sulfide treatment bed reactor (5); The second valve (82) and the second gas analyzer (92) are installed at the output end of the selective catalytic reduction reactor (6); The third valve (83) and the Fourier transform infrared spectrometer (10) are installed at the output end of the methanol oxidation catalyst reactor (7).

6. The exhaust gas treatment device according to claim 5, characterized in that, The first valve (81) is used to control the monitoring of the SO2 content by the first gas analyzer (91) of the gas output from the sulfidation bed reactor (5) x The first valve (81) is used to control the monitoring of the SO2 content by the first gas analyzer (91) of the gas output from the sulfidation bed reactor (5) x The first valve (81) is used to control the monitoring of the SO2 content by the first The second valve (82) is used to control the second gas analyzer (92) to monitor the NOx content of the gas output from the selective catalytic reduction reactor (6) x monitoring The third valve (83) is used to control the Fourier transform infrared spectrometer (10) to monitor the content of HC, CO, HCHO and CH3OH in the gas output from the methanol oxidation catalyst reactor (7).

7. The exhaust gas treatment device according to claim 1, characterized in that, The DCU control unit (11) is configured as follows: When the temperature monitored by the first temperature sensor (41) does not exceed 250°C, the heater (2) is started so that the temperature of the tail gas entering the sulfide treatment bed reactor (5) is higher than 250°C; When the temperature monitored by the first temperature sensor (41) exceeds 250°C, the heater (2) is turned off.

8. A control method for controlling the exhaust gas treatment device as described in any one of claims 1 to 7, characterized in that, Includes the following steps: The temperature of the exhaust gas discharged from the engine (12) and flowing through the exhaust pipe (1) is monitored by the first temperature sensor (41); When the monitored temperature does not exceed 250°C, the heater (2) is activated by the DCU control unit (11) to heat the exhaust gas; When the monitored temperature exceeds 250°C, the heater (2) is shut down by the DCU control unit (11). The exhaust gas is sequentially passed through the sulfide treatment bed reactor (5), the selective catalytic reduction reactor (6), and the methanol oxidation catalyst reactor (7) for treatment.

9. The method according to claim 8, characterized in that, It also includes exhaust gas composition monitoring steps: Open the first valve (81) and use the first gas analyzer (91) to monitor the SO at the output of the sulfide treatment bed reactor (5). x content; Open the second valve (82) and use the second gas analyzer (92) to monitor the NO at the output of the selective catalytic reduction reactor (6). x content; Open the third valve (83) and use the Fourier transform infrared spectrometer (10) to monitor the contents of HC, CO, HCHO and CH3OH at the output end of the methanol oxidation catalyst reactor (7).

10. A marine methanol engine exhaust gas purification system, characterized in that, Includes the exhaust gas treatment device as described in any one of claims 1 to 7, and the methanol engine (12). The exhaust port of the methanol engine (12) is connected to the input end of the exhaust pipe (1).

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