H2-SCR and NH3-SCR double-path parallel ammonia-hydrogen internal combustion engine aftertreatment system and control method

Abstract

The invention discloses an H < 2 >-SCR and NH3-SCR double-path parallel connection ammonia hydrogen internal combustion engine aftertreatment system and a control method, the treatment system comprises a first catalytic reaction branch, a second catalytic reaction branch, a third catalytic reaction branch and a fourth catalytic reaction branch, the inlet end of the first catalytic reaction branch is connected to an exhaust pipe of an ammonia hydrogen internal combustion engine, and the first catalytic reaction branch is selectively communicated with the exhaust pipe of the ammonia hydrogen internal combustion engine; wherein an ammonia gas selective catalytic reducer is arranged on the first catalytic reaction branch; the inlet end of the second catalytic reaction branch is connected to an exhaust pipe of the ammonia-hydrogen internal combustion engine and selectively communicates with the exhaust pipe of the ammonia-hydrogen internal combustion engine; a hydrogen selective catalytic reducer is arranged on the second catalytic reaction branch; the inlet end of the anti-escape treatment device is selectively communicated with the outlet end of the first catalytic reaction branch or the outlet end of the second catalytic reaction branch; wherein the anti-escape treatment device comprises a hydrogen oxidation catalyst, an ammonia escape catalyst and an N2O decomposition catalyst which are connected in sequence.

Description

Technical Field

[0001] This invention belongs to the field of internal combustion engine technology, and specifically relates to an aftertreatment system and control method for an ammonia-hydrogen internal combustion engine with H2-SCR and NH3-SCR operating in parallel. Background Technology

[0002] Traditional internal combustion engines rely on fossil fuels, accounting for nearly a quarter of global carbon emissions, necessitating zero-carbon or low-carbon alternatives. While pure hydrogen internal combustion engines can achieve zero carbon emissions, hydrogen storage and transportation costs are high, and the combustion process is prone to knocking and high concentrations of nitrogen oxides (NOx). X In contrast, ammonia (NH3), as a zero-carbon fuel, releases only nitrogen and water when burned. Liquid ammonia can be stored at atmospheric pressure and -33°C, has high energy density, a mature supply chain, and an annual production of over 200 million tons, making it a highly promising alternative fuel.

[0003] However, the slow combustion speed and difficulty in ignition of ammonia fuel limit its application in internal combustion engines. The flame propagation speed of ammonia is only one-fifth that of gasoline, resulting in low thermal efficiency and making stable combustion difficult using traditional spark ignition or compression ignition methods. Furthermore, ammonia combustion easily produces "fuel-type NO" X "The combustion pathway generates a large amount of nitrogen oxides, posing a challenge to emission control. To address these issues, researchers have proposed an ammonia-hydrogen co-combustion technology. By adding 10%-30% hydrogen, the combustion rate is significantly increased, raising the thermal efficiency to over 40%. Simultaneously, the hydrogen blending optimizes the combustion temperature distribution and reduces NO2." X generate.

[0004] However, ammonia-hydrogen engines face the challenge of low-temperature NO during cold starts. XThe purification process presents challenges, while high-load operation requires handling emissions exceeding 500℃. Existing SCR technologies have significant limitations: NH3-SCR lacks sufficient low-temperature activity, and H2-SCR suffers from poor high-temperature stability. Furthermore, ammonia-hydrogen engines emit excessive unburned ammonia, a certain amount of N2O, and hydrogen in their exhaust. Ammonia has a strong, irritating odor; even low-concentration exposure can harm the respiratory system and eyes, while high-concentration leaks could even trigger an explosion. Moreover, escaped ammonia, once in the atmosphere, reacts with acidic substances to form secondary particulate matter (such as ammonium nitrate), exacerbating smog pollution. N2O is a potent greenhouse gas with a global warming potential 265 times greater than CO2, and it can persist in the atmosphere for a long time, having a far greater impact on climate change than conventional exhaust components. Simultaneously, N2O depletes the ozone layer, further threatening the ecological environment. Hydrogen is a flammable and explosive gas with a wide explosion limit range (4%–75% by volume in air); even small leaks can form hazardous mixtures in certain environments. Even more challenging is that new regulations such as Euro 7 impose stricter requirements on cold-start emissions, which traditional solutions can no longer meet.

[0005] Developing a full-temperature aftertreatment system requires integrating low-temperature adsorption, intermediate-temperature catalysis, and high-temperature stabilization technologies, and achieving NO reduction within the 50-600℃ range through multi-mode synergistic control. X The conversion rate is >95%, and it provides an effective after-treatment solution for handling unburned ammonia, N2O, and excess hydrogen. This is of decisive significance for meeting relevant emission regulations and promoting the development of zero-carbon power.

[0006] Patent CN115111031A proposes an emission treatment scheme for an ammonia-hydrogen fuel power system. It employs an in-cylinder ion current sensor and an external multi-sensor array (including nitrogen oxide, temperature, and ammonia sensors) to achieve precise pollutant monitoring, and uses a closed-loop control system via an ammonia injection system to optimize reduction efficiency. This system utilizes multiple sensors to regulate the ammonia supply to the ammonia cracker, improving in-cylinder combustion quality, and employs an electrically heated catalytic module to increase the cold-start exhaust temperature, effectively solving the problem of high ammonia and high nitrogen oxide emissions during the cold start phase of traditional ammonia-fuel engines. However, this technical solution has significant limitations: firstly, it does not fully consider the impact of hydrogen emissions from the ammonia-hydrogen mixed combustion on the aftertreatment system; secondly, it fails to effectively utilize hydrogen in the exhaust as a reducing agent to improve nitrogen oxide treatment efficiency, which to some extent limits the overall performance optimization potential of the system.

[0007] Patent CN117072287A proposes an emission treatment system for ammonia / ammonia-hydrogen fuel engines. This system incorporates a three-way catalytic converter on the exhaust pipe, simultaneously treating ammonia, nitrogen oxides, and nitrous oxide. The system achieves closed-loop control through ammonia sensors before and after the catalytic converter and is equipped with an ammonia injection device to optimize reaction efficiency. While this solution addresses the issue of insufficient ignition temperature during cold start-up, it has a significant drawback: under cold start conditions, the ammonia-hydrogen fuel engine produces high-concentration hydrogen emissions, and the system does not consider hydrogen treatment. This poses a backfire safety hazard and misses the opportunity to optimize the catalytic reaction by utilizing hydrogen.

[0008] Patent CN119754907A proposes an aftertreatment system and method for an ammonia / ammonia-hydrogen internal combustion engine with tightly coupled H2-SCR. This system utilizes the residual hydrogen during cold start to participate in the reduction of NO by using an H2-SCR and an NH3-SCR in series. X The system operates within a reaction process. Multiple sensors detect the concentration and temperature of various components in the exhaust gas, providing feedback to the controller for precise control of the ammonia injection rate. While this system achieves the goal of reducing NO2 during cold starts in ammonia-hydrogen engines... X While the goal of emission reduction and improved fuel utilization was achieved, the significant reduction in the activity of H2-SCR catalysts at high temperatures and their susceptibility to physical sintering greatly impaired the lifespan of H2-SCR. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide an ammonia-hydrogen internal combustion engine aftertreatment system with H2-SCR and NH3-SCR connected in parallel. By connecting the hydrogen selective catalytic reduction (H2-SCR) and the ammonia selective catalytic reduction (NH3-SCR) in parallel, it can achieve full coverage of the exhaust temperature conditions of the internal combustion engine, avoid cross-interference between the reducing agent and the products, and solve the problem of H2-SCR deactivation at high temperatures.

[0010] This invention also provides a control method for an ammonia-hydrogen internal combustion engine aftertreatment system with H2-SCR and NH3-SCR operating in parallel. This method adjusts the operating state of the treatment system in real time according to the exhaust conditions of the internal combustion engine, enabling the control of NO emissions. X Highly efficient conversion.

[0011] The technical solution provided by this invention is as follows:

[0012] A dual-path parallel H2-SCR and NH3-SCR aftertreatment system and control method for an ammonia-hydrogen internal combustion engine, comprising:

[0013] The first catalytic reaction branch has its inlet end connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine and is selectively connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine.

[0014] An ammonia selective catalytic reduction device is provided in the first catalytic reaction branch;

[0015] The second catalytic reaction branch has its inlet end connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine and is selectively connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine.

[0016] A hydrogen selective catalytic reducer is provided in the second catalytic reaction branch;

[0017] An escape prevention treatment device, the inlet end of which is selectively connected to the outlet end of the first catalytic reaction branch or the outlet end of the second catalytic reaction branch;

[0018] The escape prevention device includes a hydrogen oxidation catalyst, an ammonia escape catalyst, and an N2O decomposition catalyst connected in sequence.

[0019] Preferably, the ammonia-hydrogen internal combustion engine aftertreatment system with H2-SCR and NH3-SCR operating in parallel further includes:

[0020] A first electrically heated catalyst is disposed on the first catalytic reaction branch and located before the ammonia selective catalytic reduction unit;

[0021] A second electrically heated catalyst is disposed on the second catalytic reaction branch and located before the hydrogen selective catalytic reduction unit.

[0022] Preferably, the ammonia-hydrogen internal combustion engine aftertreatment system with H2-SCR and NH3-SCR operating in parallel further includes:

[0023] An ammonia nozzle is disposed at the inlet of the ammonia selective catalytic reduction unit for injecting ammonia into the ammonia selective catalytic reduction unit.

[0024] A hydrogen nozzle, which is disposed at the inlet of the hydrogen selective catalytic reduction unit, is used to inject hydrogen into the hydrogen selective catalytic reduction unit.

[0025] Preferably, a first electric butterfly valve and a second electric butterfly valve are respectively provided at the inlet and outlet ends of the first catalytic reaction branch.

[0026] The inlet and outlet ends of the second catalytic reaction branch are respectively equipped with a third electric butterfly valve and a fourth electric butterfly valve.

[0027] Preferably, the exhaust pipe of the ammonia-hydrogen internal combustion engine is equipped with a first temperature sensor, a first ammonia sensor, a first hydrogen sensor and a first nitrogen oxide sensor;

[0028] A second temperature sensor is installed at the outlet end of the first electrically heated catalyst.

[0029] A third temperature sensor is installed at the outlet end of the second electrically heated catalyst;

[0030] A second ammonia sensor is provided at the outlet end of the first catalytic reaction branch;

[0031] A second hydrogen sensor is provided at the outlet end of the second catalytic reaction branch;

[0032] A second nitrogen oxide sensor is installed in the pipeline at the inlet end of the escape prevention treatment device.

[0033] Preferably, the ammonia-hydrogen internal combustion engine aftertreatment system with H2-SCR and NH3-SCR operating in parallel further includes:

[0034] The controller is electrically connected to the ammonia nozzle, the hydrogen nozzle, the first electric butterfly valve, the second electric butterfly valve, the third electric butterfly valve, and the fourth electric butterfly valve, respectively.

[0035] A control method for an aftertreatment system of an ammonia-hydrogen internal combustion engine with H2-SCR and NH3-SCR operating in parallel, for controlling the treatment system, comprising:

[0036] Real-time monitoring of the exhaust temperature T of the ammonia-hydrogen internal combustion engine;

[0037] When T < 250℃, the inlet end of the second catalytic reaction branch is connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine, and the outlet end is connected to the anti-escape treatment device; the inlet and outlet ends of the first catalytic reaction branch are closed.

[0038] When 250℃≤T<400℃, the inlet end of the first catalytic reaction branch and the inlet end of the second catalytic reaction branch are simultaneously connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine, and the outlet end of the first catalytic reaction branch and the outlet end of the second catalytic reaction branch are simultaneously connected to the escape prevention treatment device.

[0039] When T≥400℃, the inlet end of the first catalytic reaction branch is connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine, and the outlet end is connected to the anti-escape treatment device; the inlet and outlet ends of the second catalytic reaction branch are closed.

[0040] Preferably, the control method for the ammonia-hydrogen internal combustion engine aftertreatment system with H2-SCR and NH3-SCR operating in parallel further includes:

[0041] When the first catalytic reaction branch is turned on, the outlet gas temperature t1 of the first electrically heated catalyst is monitored in real time.

[0042] When t1 < 250℃, start the first electrically heated catalyst until t1 rises to 300℃;

[0043] When the second catalytic reaction branch is turned on, the outlet gas temperature t2 of the second electrically heated catalyst is monitored in real time.

[0044] When t2 < 150℃, start the second electrically heated catalyst until t2 rises to 200℃.

[0045] Preferably, the control method for the ammonia-hydrogen internal combustion engine aftertreatment system with H2-SCR and NH3-SCR operating in parallel further includes:

[0046] Real-time monitoring of hydrogen concentration in the exhaust pipe of an ammonia-hydrogen internal combustion engine ammonia concentration and nitrogen oxide concentration

[0047] When the first catalytic reaction branch is activated, and At that time, ammonia gas is injected into the ammonia selective catalytic reduction unit;

[0048] When the second catalytic reaction branch is activated, and At that time, hydrogen is injected into the hydrogen selective catalytic reduction unit.

[0049] Preferably, the control method for the ammonia-hydrogen internal combustion engine aftertreatment system with H2-SCR and NH3-SCR operating in parallel further includes:

[0050] Real-time monitoring of ammonia concentration at the outlet of the first catalytic reaction branch, hydrogen concentration at the outlet of the second catalytic reaction branch, and nitrogen oxide concentration at the inlet of the escape prevention treatment device;

[0051] The amount of ammonia and hydrogen injected is adjusted based on the ammonia concentration at the outlet of the first catalytic reaction branch, the hydrogen concentration at the outlet of the second catalytic reaction branch, and the nitrogen oxide concentration at the inlet of the escape prevention treatment device.

[0052] The beneficial effects of this invention are:

[0053] (1) This invention addresses the rear exhaust characteristics of ammonia-hydrogen engines by designing a dual-path parallel aftertreatment system for ammonia-hydrogen internal combustion engines, utilizing the high denitrification efficiency of H2-SCR in the low-temperature range, thus solving the problem of reducing NO during cold starts. X The challenge lies in combining the advantages of NH3-SCR's high-temperature performance, which covers the entire operating temperature window and improves the denitrification efficiency of the system under all operating conditions. By using H2-SCR and NH3-SCR in parallel, the cross-interference between the reducing agent and the product can be avoided, and the sintering and deactivation of the precious metal catalyst of H2-SCR can be prevented.

[0054] (2) The present invention adds electric butterfly valves before and after the hydrogen selective catalytic reduction unit and the ammonia selective catalytic reduction unit respectively. By controlling the electric butterfly valves through the controller, the opening and closing state of the electric butterfly valves can be adjusted according to different working conditions, thereby implementing appropriate after-treatment schemes and reducing pollutant emissions.

[0055] (3) This invention incorporates a temperature sensor and NO... X Sensors, including hydrogen and ammonia sensors, detect exhaust temperature and NO in the exhaust. X The concentrations of hydrogen and ammonia components are determined, and a post-treatment scheme is selected according to the temperature. The amount of reducing agent required for each reaction is calculated and injected. The system efficiency is calculated through a second nitrogen oxide sensor to compensate for system errors. The reducing agent concentration sensor after each branch is used to diagnose whether the reducing agent injection is excessive, and the reducing agent injection amount is dynamically optimized to achieve the purpose of precise control system.

[0056] (4) The present invention uses an anti-escape device composed of a hydrogen oxidation catalyst, an ammonia escape catalyst and a nitrous oxide decomposition catalyst to eliminate excess hydrogen, ammonia and high greenhouse gas N2O generated during the after-treatment process, thereby improving the purification effect of internal combustion engine exhaust. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the aftertreatment system for an ammonia-hydrogen internal combustion engine with H2-SCR and NH3-SCR operating in parallel as described in this invention.

[0058] Figure 2 This is a flowchart of the control method for the aftertreatment system of an ammonia-hydrogen internal combustion engine with H2-SCR and NH3-SCR in parallel as described in this invention. Detailed Implementation

[0059] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0060] like Figure 1 As shown, the present invention provides an aftertreatment system for an ammonia-hydrogen internal combustion engine with H2-SCR and NH3-SCR operating in parallel. Figure 1The components and their corresponding reference numerals are as follows: Hydrogen tank 1, Ammonia-hydrogen internal combustion engine 2, Ammonia tank 3, First electric butterfly valve 4, First electrically heated catalytic converter (EHC) 5, Second temperature sensor 6, Ammonia nozzle 7, Ammonia selective catalytic reduction converter 8, Second electric butterfly valve 9, Second ammonia sensor 10, N2O decomposition catalyst 11, Ammonia escape catalyst 12, Hydrogen oxidation catalyst 13, Second nitrogen oxide sensor 14, Second hydrogen sensor 15, Fourth electric butterfly valve 16, Hydrogen selective catalytic reduction converter 17, Hydrogen nozzle 18, Third temperature sensor 19, Second electrically heated catalytic converter (EHC) 20, Third electric butterfly valve 21, First nitrogen oxide sensor 22, First hydrogen sensor 23, First ammonia sensor 24, First temperature sensor 25, Controller 26, Spark plug 27, Intake manifold ammonia injector 28, First pressure reducing valve 29, Second pressure reducing valve 30, In-cylinder hydrogen direct injection 31, Third pressure reducing valve 32, Fourth pressure reducing valve 33.

[0061] The connection relationships of hydrogen tank 1, ammonia-hydrogen internal combustion engine 2, ammonia tank 3, spark plug 27, intake manifold ammonia injector 28, and in-cylinder hydrogen direct injector 31 are all standard settings for ammonia-hydrogen internal combustion engines and will not be described in detail here.

[0062] The ammonia-hydrogen internal combustion engine aftertreatment system with H2-SCR and NH3-SCR in parallel includes: a first catalytic reaction branch, a second catalytic reaction branch, and an escape prevention treatment device.

[0063] The inlet end of the first catalytic reaction branch is connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine 2, and is selectively connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine 2. An ammonia selective catalytic reduction device 8 is installed on the first catalytic reaction branch.

[0064] As a preferred option, the catalyst for the ammonia selective catalytic reduction unit 8 is a molecular sieve catalyst, specifically one of Cu-ZSM-5, Fe-ZSM-5, Fe-BEA, and Cu-BEA molecular sieves. Using a molecular sieve catalyst can improve the low-temperature treatment effect.

[0065] The inlet end of the second catalytic reaction branch is connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine 2, and is selectively connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine 2. A hydrogen selective catalytic reduction unit 17 is installed on the second catalytic reaction branch.

[0066] As a preferred embodiment, the catalyst of the hydrogen selective catalytic reduction unit 17 is a noble metal catalyst, which is a platinum (Pt), palladium (Pd), or rhodium (Rh) oxide or a Pt-Pd or Pt-Rh bimetallic catalyst. The noble metal catalyst is supported on a support such as alumina or titanium dioxide.

[0067] As a further preferred option, the hydrogen selective catalytic reduction (SCR) incorporates rare earth oxides such as CeO2 and ZrO2 as additives. This enhances oxygen storage capacity and metal-support interaction, thereby improving sulfur resistance (SO4). X ), phosphorus resistance (PO) X Poisoning resistance (e.g., CeO2-modified Pt / Al2O3 catalyst has a 30% higher sulfur tolerance).

[0068] The inlet of the anti-escape treatment device is selectively connected to the outlet of either the first catalytic reaction branch or the outlet of the second catalytic reaction branch. The anti-escape treatment device includes a hydrogen oxidation catalyst 13, an ammonia escape catalyst 12, and an N2O decomposition catalyst 11, connected sequentially along the exhaust flow direction.

[0069] The ammonia escape catalyst 12 is installed to prevent ammonia leakage and meet the 10×10 standard. -6 The ammonia leakage requirement is ppm. The catalyst of the ammonia escape catalyst 12 is made of noble metal alloy or noble metal oxide, wherein the noble metal alloy is mainly platinum-palladium alloy or silver-copper alloy; the noble metal oxide is mainly oxide of platinum, palladium and rhodium. The support material of the ammonia escape catalyst 12 is a ceramic honeycomb support or a metal support.

[0070] When ammonia-hydrogen engines burn fuel, nitrogen in ammonia readily converts into nitrous oxide (N2O) under high temperature or catalytic conditions, which has a greenhouse effect approximately 265 times that of carbon dioxide. By installing an N2O decomposition catalyst 11, N2O is converted into nitrogen and oxygen using a catalyst (such as a precious metal or molecular sieve), effectively reducing greenhouse gas emissions and meeting carbon neutrality goals and stringent environmental regulations.

[0071] To prevent escaped ammonia from entering the N2O decomposition catalyst 11 and being directly oxidized to NO X To avoid increasing emissions, the present invention installs the ammonia escape catalyst 12 before the N2O decomposition catalyst 11.

[0072] The catalyst active components of the N2O decomposition catalyst 11 include transition metal oxides, noble metals, and molecular sieves. Specifically, the transition metal oxides are oxides of copper, iron, and manganese; the noble metals include platinum and rhodium; and the molecular sieves are Cu-ZSM-5 or Fe-BEA.

[0073] The N2O decomposition catalyst 11 uses cordierite honeycomb ceramic and Fe-Cr-Al metal mesh as the support material, providing a high specific surface area and high temperature resistant support structure; the γ-Al2O3 or CeO2-ZrO2 composite oxide coating enhances the dispersion of active sites.

[0074] Because hydrogen leaks in ammonia-hydrogen engines can easily form explosive mixtures, which can ignite and explode upon contact with an open flame, and because hydrogen consumes atmospheric hydroxyl radicals, prolonging the lifespan of methane and exacerbating the greenhouse effect, this invention incorporates a hydrogen oxidation catalyst 13 within the escape prevention device to handle excess hydrogen.

[0075] Since the hydrogen oxidation catalyst 13 oxidizes hydrogen and releases heat, it can preheat the ammonia escape catalyst 12 and improve its low-temperature activity. At the same time, the hydrogen is eliminated first to avoid interfering with the ammonia reduction reaction in the ammonia escape catalyst 12. Therefore, the hydrogen oxidation catalyst 13 is installed before the ammonia escape catalyst 12.

[0076] The catalyst material of the hydrogen oxidation catalyst 13 is a noble metal catalyst or a non-noble metal catalyst. The noble metal catalyst includes platinum, palladium and gold, and the non-noble metal catalyst includes transition metal oxides, such as copper oxide (CuO), cobalt oxide (Co3O4) and manganese oxide (MnO2).

[0077] The support structure materials of the hydrogen oxidation catalyst 13 are oxide support and high temperature resistant support.

[0078] In this embodiment, the exhaust pipe outlet of the ammonia-hydrogen internal combustion engine 2 is connected to the inlet ends of the first catalytic reaction branch and the second catalytic reaction branch via a Y-shaped tee pipe; the inlet end of the anti-escape treatment device is connected to the outlet ends of the first catalytic reaction branch and the second catalytic reaction branch via a Y-shaped tee pipe. To reduce back pressure, the pipes of the first catalytic reaction branch and the second catalytic reaction branch are arranged symmetrically.

[0079] The first catalytic reaction branch includes, along the exhaust flow direction, a first electric butterfly valve 4, a first electrically heated catalyst (EHC) 5, an ammonia selective catalytic reduction device 8, and a second electric butterfly valve 9 connected in sequence.

[0080] The second catalytic reaction branch includes, along the exhaust flow direction, a third electric butterfly valve 21, a second electrically heated catalyst (EHC) 20, a hydrogen selective catalytic reduction device 17, and a fourth electric butterfly valve 16 connected in sequence.

[0081] The first electrically heated catalyst (EHC) 5 and the second electrically heated catalyst (EHC) 20 are powered by an on-board battery.

[0082] Both the first and second catalytic reaction branches are equipped with EHC auxiliary devices, which enable the ammonia selective catalytic reducer 8 and the hydrogen selective catalytic reducer 17 to reach their minimum operating temperatures at low temperatures.

[0083] A second temperature sensor 6 and a third temperature sensor 19 are respectively installed at the outlet ends of the first electric heating catalyst (EHC) 5 and the second electric heating catalyst (EHC) 20 to detect the temperature of the exhaust gas after being heated by the first electric heating catalyst (EHC) 5 and the second electric heating catalyst (EHC) 20, and to determine whether the minimum operating temperature of the ammonia selective catalytic reduction device 8 and the hydrogen selective catalytic reduction device 17 has been reached.

[0084] As a preferred embodiment, both the first electrically heated catalyst (EHC) 5 and the second electrically heated catalyst (EHC) 20 adopt a honeycomb structure, with the inner filling material made of ceramic material, and then the catalyst is deposited on the inner filling material. Preferably, the ceramic material is silicon carbide; the catalyst of the electrically heated catalyst is a noble metal catalyst, such as platinum or palladium.

[0085] In this embodiment, the first electric butterfly valve 4, the second electric butterfly valve 9, the third electric butterfly valve 20, and the fourth electric butterfly valve 16 are all driven by high-precision servo motors and equipped with PTFE sealed valve seats (temperature resistance -20 to 150℃). The valve bodies are made of CF8M stainless steel (corrosion resistant) to adapt to the intelligent fluid control system.

[0086] An ammonia nozzle 7 is provided at the inlet of the ammonia selective catalytic reduction unit 8 for injecting (replenishing) ammonia into the ammonia selective catalytic reduction unit 8. A hydrogen nozzle 18 is provided at the inlet of the hydrogen selective catalytic reduction unit 17 for injecting (replenishing) hydrogen into the hydrogen selective catalytic reduction unit 17.

[0087] Ammonia tank 3 is connected to intake manifold ammonia injector 28 via a first ammonia pipeline, and intake manifold ammonia injector 28 injects ammonia into ammonia-hydrogen internal combustion engine 2; hydrogen tank 1 is connected to in-cylinder hydrogen direct injector 31 via a first hydrogen pipeline, and in-cylinder hydrogen direct injector 31 injects hydrogen into ammonia-hydrogen internal combustion engine 2.

[0088] Ammonia nozzle 7 is connected to ammonia tank 3 via a second ammonia pipeline, and hydrogen nozzle 18 is connected to hydrogen tank 1 via a second hydrogen pipeline.

[0089] The first hydrogen pipeline, the second hydrogen pipeline, the first ammonia pipeline, and the second ammonia pipeline are respectively equipped with a second pressure reducing valve 30, a first pressure reducing valve 29, a third pressure reducing valve 32, and a fourth pressure reducing valve 33.

[0090] The exhaust pipe of the ammonia-hydrogen internal combustion engine 2 is equipped with a first temperature sensor 25, a first ammonia sensor 24, a first hydrogen sensor 23 and a first nitrogen oxide sensor 22, which are used to detect the gas (exhaust gas) temperature, ammonia concentration, hydrogen concentration and nitrogen oxide concentration in the exhaust pipe of the ammonia-hydrogen internal combustion engine 2, respectively.

[0091] A second ammonia sensor 10 is provided at the outlet end of the first catalytic reaction branch (after the second electric butterfly valve 9) to detect the concentration of ammonia in the gas after it has been processed by the first catalytic reaction branch.

[0092] A second hydrogen sensor 15 is provided at the outlet end of the second catalytic reaction branch (after the fourth electric butterfly valve 16) to detect the concentration of hydrogen in the gas after it has been processed by the second catalytic reaction branch.

[0093] A second nitrogen oxide sensor 14 is installed in the pipeline at the inlet end of the escape prevention treatment device to detect the concentration of nitrogen oxides in the gas after being treated by the first catalytic reaction branch and the second catalytic reaction branch.

[0094] The aforementioned ammonia-hydrogen internal combustion engine aftertreatment system with H2-SCR and NH3-SCR dual parallel circuits further includes a controller 26, which is electrically connected to the ammonia nozzle 7, hydrogen nozzle 18, first electric butterfly valve 4, second electric butterfly valve 9, third electric butterfly valve 21, and fourth electric butterfly valve 16, respectively. The controller 26 receives detection information from the first temperature sensor 25, second temperature sensor 6, third temperature sensor 19, first ammonia sensor 24, first hydrogen sensor 23, first nitrogen oxide sensor 22, second ammonia sensor 10, second hydrogen sensor 15, and second nitrogen oxide sensor 14, and controls the ammonia nozzle 7, hydrogen nozzle 18, first electric butterfly valve 4, second electric butterfly valve 9, third electric butterfly valve 19, and fourth electric butterfly valve 16 according to the detection information, thereby switching the working state of the first catalytic reaction branch and the second catalytic reaction branch.

[0095] The first electrically heated catalyst (EHC) 5 and the second electrically heated catalyst (EHC) 20 are also electrically connected to the controller 26, which controls their opening or closing.

[0096] The ammonia-hydrogen mixture is burned in the cylinder of the ammonia-hydrogen internal combustion engine 2. The exhaust gas contains unburned ammonia (NH3) and hydrogen (H2), as well as a certain amount of nitrogen oxides (NOx). X The combustion exhaust gases, consisting of nitrous oxide (N2O) and nitrogen oxides, flow out through the exhaust pipe and enter the treatment system. Sensors installed inside the exhaust pipe detect the concentration of components in the combustion exhaust gases and the exhaust temperature, transmitting the signals to the controller 26. The controller 26 controls the electric butterfly valve to adjust the flow rates into the two branches, the amount of ammonia injected from the ammonia tank 3 into the ammonia selective catalytic reduction (NH3-SCR) 8, and the amount of hydrogen injected from the hydrogen tank 1 into the hydrogen selective catalytic reduction (H2-SCR) 17 through the hydrogen nozzle 18.

[0097] Because H2-SCR has high denitrification efficiency in the low-temperature range (150-300℃) and NH3-SCR has excellent performance in the medium-high temperature range (250-500℃), the two complement each other to cover the entire operating temperature range. Moreover, the system can simultaneously utilize the native hydrogen and ammonia in the exhaust gas as reducing agents, improving resource utilization. In addition, the dual-path design can enhance system reliability. Even when one catalyst fails, it can still maintain part of the denitrification capacity to ensure that emissions meet standards. Therefore, the parallel catalytic reactor is arranged with two independent catalytic reduction paths, H2-SCR and NH3-SCR, which can be intelligently switched or mixed according to operating conditions.

[0098] During cold starts, the ammonia-hydrogen engine experiences low cylinder temperatures and poor fuel atomization, resulting in a significant increase in the emission of unburned ammonia and hydrogen in the exhaust gas. The amount of nitrogen oxides generated fluctuates and decreases due to insufficient combustion temperature. At this time, the selective reduction reaction of hydrogen and nitrogen oxides can be carried out by utilizing excess hydrogen and exhaust temperature, which can effectively remove excess hydrogen and reduce nitrogen oxides.

[0099] After warm-up, the cylinder temperature of the ammonia-hydrogen engine rises to the optimal combustion range, significantly reducing the emissions of unburned ammonia and hydrogen. Nitrogen oxides show an upward trend due to high-temperature combustion. The catalytic system reaches its active temperature, and excess hydrogen and ammonia are efficiently converted through after-treatment such as SCR. The concentration of pollutants in the exhaust gas tends to stabilize, and the overall emission performance is close to the design conditions. The appropriate catalytic reduction path is selected according to the specific component concentration.

[0100] At high temperatures, combustion in the cylinder of an ammonia-hydrogen engine is intense, further reducing the emissions of unburned ammonia and hydrogen. However, high temperatures significantly increase the generation of nitrogen oxides. Although the catalytic system has high activity, high temperatures may cause thermal deactivation of the catalyst. Furthermore, hydrogen is prone to non-selective oxidation in an oxygen-rich environment. In this case, selective reduction of ammonia as the main pathway can significantly improve the high-temperature stability of the system.

[0101] Furthermore, a second hydrogen sensor, a second ammonia sensor, and a second nitrogen oxide sensor are installed at the exhaust outlet of the parallel catalytic reactor to evaluate the performance of each branch of the parallel catalytic reactor and the overall reduction of NO. X The system monitors emission data in real time and feeds it back to the controller to dynamically adjust the amount of reactant injected. A second temperature sensor 6 and a third temperature sensor 19 are installed after the EHC (electric heating auxiliary device) of each branch to detect the temperature of the heated gas in real time. In addition, a second hydrogen sensor 15 is installed after the fourth electric butterfly valve 16 and a second ammonia sensor 10 is installed after the second electric butterfly valve 9 to evaluate the reducing agent injection effect of the corresponding branch. All of the above sensors are connected to the controller 26 and are subject to the precise control of the controller.

[0102] like Figure 2As shown, the present invention also provides a control method for an ammonia-hydrogen internal combustion engine aftertreatment system with H2-SCR and NH3-SCR connected in parallel, and the specific implementation process is as follows.

[0103] The exhaust temperature T of the ammonia-hydrogen internal combustion engine 2 is monitored in real time by the first temperature sensor 25, as well as the hydrogen concentration in the exhaust pipe of the ammonia-hydrogen internal combustion engine. ammonia concentration and nitrogen oxide concentration .

[0104] (1) When T < 250℃, H2-SCR is used to reduce NO in exhaust gas. X The controller 26 controls the third electric butterfly valve 21 and the fourth electric butterfly valve 16 to be fully open, so that the inlet end of the second catalytic reaction branch is connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine, and the outlet end is connected to the anti-escape treatment device (the second catalytic reaction branch is open); at the same time, it controls the first electric butterfly valve 4 and the second electric butterfly valve 9 to be closed, so that the inlet end and the outlet end of the first catalytic reaction branch are closed (the first catalytic reaction branch is closed).

[0105] Simultaneously based on hydrogen concentration and nitrogen oxide concentration Determine whether to inject additional hydrogen.

[0106] like Then there is no need to re-spray H2; if Then control the hydrogen nozzle to spray hydrogen into the hydrogen selective catalytic reduction unit.

[0107] The hydrogen injection quantity is calculated using the following formula:

[0108]

[0109] In the formula, The mass flow rate of H2 injection is (g / s), and γ is the conversion factor between volumetric flow rate and molar flow rate. V m (where is the molar volume of a gas under a given state). Let H2 be the molar mass and Q be the exhaust gas volumetric flow rate (m³ / s). 3 / s), where β is the stoichiometric ratio obtained based on the standard SCR reaction, and in this embodiment, β = 1.

[0110] (2) When 250℃≤T<400℃, H2-SCR and NH3-SCR work together, with each treating 50% of the exhaust gas. The controller fully opens the first electric butterfly valve 4, the second electric butterfly valve 9, the third electric butterfly valve 21, and the fourth electric butterfly valve 16, simultaneously connecting the inlet of the first catalytic reaction branch and the inlet of the second catalytic reaction branch to the exhaust pipe of the ammonia-hydrogen internal combustion engine, and simultaneously connecting the outlet of the first catalytic reaction branch and the outlet of the second catalytic reaction branch to the anti-escape treatment device. (The first and second catalytic reaction branches are opened simultaneously.)

[0111] Simultaneously based on hydrogen concentration ammonia concentration and nitrogen oxide concentration Determine whether to inject additional hydrogen or ammonia.

[0112] like No need to inject additional hydrogen; if Then control the hydrogen nozzle to spray hydrogen into the hydrogen selective catalytic reduction unit.

[0113] like No need to spray ammonia, if When necessary, the ammonia nozzle is controlled to inject ammonia gas into the ammonia selective catalytic reduction unit.

[0114] The formula for calculating the H2 injection volume is as follows:

[0115]

[0116] The formula for calculating the NH3 injection quantity is:

[0117]

[0118] In the formula, The mass flow rate of H2 injection is (g / s). γ is the mass flow rate of NH3 injection (g / s), and γ is the conversion factor between volumetric flow rate and molar flow rate. V m Q is the molar volume of a gas under certain conditions, and Q is the volumetric flow rate of the waste gas (m³). 3 / s), The molar mass of H2 α represents the molar mass of NH3, and β represents the stoichiometric ratios obtained based on the standard SCR reaction, both of which are 1.

[0119] (3) When T≥400℃, NH3-SCR is used to reduce NO in exhaust gas. XThe controller controls the first electric butterfly valve 4 and the second electric butterfly valve 9 to be fully open, and the third electric butterfly valve 21 and the fourth electric butterfly valve 16 to be closed, so that the inlet end of the first catalytic reaction branch is connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine, and the outlet end is connected to the anti-escape treatment device (the first catalytic reaction branch is open); the inlet end and the outlet end of the second catalytic reaction branch are closed (the second catalytic reaction branch is closed).

[0120] Simultaneously based on ammonia concentration and nitrogen oxide concentration Determine whether to spray additional ammonia.

[0121] like No need to spray ammonia, if When necessary, the ammonia nozzle is controlled to inject ammonia gas into the ammonia selective catalytic reduction unit.

[0122] The injection quantity of NH3 is calculated using the following formula:

[0123]

[0124] In the formula, γ is the mass flow rate of NH3 injection (g / s), and γ is the conversion factor between volumetric flow rate and molar flow rate. V m Q is the molar volume of a gas under certain conditions, and Q is the volumetric flow rate of the waste gas (m³ / s). 3 / s), α is the molar mass of NH3, and α is the stoichiometric ratio obtained based on the standard SCR reaction. In this example, α = 1.

[0125] When the corresponding branch is turned on, if the SCR temperature of that branch is detected to be lower than the optimal temperature window, then an electric heating catalyst auxiliary heating method must be used. The specific steps are as follows:

[0126] When the first catalytic reaction branch is turned on, if the second temperature sensor 6 detects that the gas temperature t1 discharged through the first electric heating catalyst 5 is less than 250°C, then the first electric heating catalyst 5 in the first catalytic reaction branch is activated so that t1 quickly reaches 300°C.

[0127] When the second catalytic reaction branch is turned on, if the third temperature sensor 19 detects that the gas temperature t2 discharged through the first electric heating catalyst is less than 150°C, then the second electric heating catalyst 20 on the second catalytic reaction branch is activated so that t2 quickly reaches 200°C.

[0128] This invention also includes real-time monitoring of the ammonia concentration at the outlet of the first catalytic reaction branch, the ammonia concentration at the outlet of the second catalytic reaction branch, and the nitrogen oxide concentration at the inlet of the escape prevention treatment device. If the ammonia concentration at the outlet of the first catalytic reaction branch exceeds a set threshold, it is determined that the amount of supplementary ammonia is excessive, and the ammonia nozzle injection rate is reduced. If the hydrogen concentration at the outlet of the second catalytic reaction branch exceeds a set threshold, it is determined that the amount of supplementary hydrogen is excessive, and the hydrogen nozzle injection rate is reduced. The nitrogen oxide conversion rate of the treatment system is calculated based on the nitrogen oxide concentration at the inlet of the escape prevention treatment device and fed back to the controller. The controller calculates the NO... X Conversion rate, and based on NO X The conversion rate compensates for errors in the amount of hydrogen and ammonia injected, enabling dynamic adjustment of the reducing agent injection amount and achieving the goal of a precise control system.

[0129] This invention features a hydrogen selective catalytic reduction (HCR) unit and an ammonia selective catalytic reduction (ACR) unit on two separate catalytic reaction branches. Each reducer is equipped with an EHC (Electronic Harmonic Control) system to maintain a minimum operating temperature. Electric butterfly valves control gas flow rates before and after each pipeline. Detection devices are installed in the exhaust pipes before and after the catalytic reactors. Based on the controller's analysis of the front-end data, appropriate aftertreatment strategies and the injection amount of supplemental reducing agent are selected. Back-end data is used to calculate NO. X The conversion rate is dynamically adjusted to control the injection volume of each reducing agent under the next operating condition. This invention can effectively cover all temperature conditions of exhaust gas emissions, enabling the catalyst to operate within its optimal activity window and improving the conversion efficiency of pollutants.

[0130] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. An aftertreatment system for an ammonia-hydrogen internal combustion engine with H2-SCR and NH3-SCR operating in parallel, characterized in that, include: The first catalytic reaction branch has its inlet end connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine and is selectively connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine. An ammonia selective catalytic reduction device is provided in the first catalytic reaction branch; The second catalytic reaction branch has its inlet end connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine and is selectively connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine. A hydrogen selective catalytic reducer is provided in the second catalytic reaction branch; An escape prevention treatment device, the inlet end of which is selectively connected to the outlet end of the first catalytic reaction branch or the outlet end of the second catalytic reaction branch; The escape prevention device includes a hydrogen oxidation catalyst, an ammonia escape catalyst, and an N2O decomposition catalyst connected in sequence.

2. The ammonia-hydrogen internal combustion engine aftertreatment system with H2-SCR and NH3-SCR dual parallel circuits as described in claim 1, characterized in that, Also includes: A first electrically heated catalyst is disposed on the first catalytic reaction branch and located before the ammonia selective catalytic reduction unit; A second electrically heated catalyst is disposed on the second catalytic reaction branch and located before the hydrogen selective catalytic reduction unit.

3. The ammonia-hydrogen internal combustion engine aftertreatment system with H2-SCR and NH3-SCR dual parallel circuits as described in claim 2, characterized in that, Also includes: An ammonia nozzle is disposed at the inlet of the ammonia selective catalytic reduction unit for injecting ammonia into the ammonia selective catalytic reduction unit. A hydrogen nozzle, which is disposed at the inlet of the hydrogen selective catalytic reduction unit, is used to inject hydrogen into the hydrogen selective catalytic reduction unit.

4. The ammonia-hydrogen internal combustion engine aftertreatment system with H2-SCR and NH3-SCR dual-path parallel operation according to any one of claims 1-3, characterized in that, The inlet and outlet ends of the first catalytic reaction branch are respectively equipped with a first electric butterfly valve and a second electric butterfly valve. The inlet and outlet ends of the second catalytic reaction branch are respectively equipped with a third electric butterfly valve and a fourth electric butterfly valve.

5. The ammonia-hydrogen internal combustion engine aftertreatment system with H2-SCR and NH3-SCR dual parallel circuits as described in claim 4, characterized in that, The exhaust pipe of the ammonia-hydrogen internal combustion engine is equipped with a first temperature sensor, a first ammonia sensor, a first hydrogen sensor and a first nitrogen oxide sensor. A second temperature sensor is installed at the outlet end of the first electrically heated catalyst. A third temperature sensor is installed at the outlet end of the second electrically heated catalyst; A second ammonia sensor is provided at the outlet end of the first catalytic reaction branch; A second hydrogen sensor is provided at the outlet end of the second catalytic reaction branch; A second nitrogen oxide sensor is installed in the pipeline at the inlet end of the escape prevention treatment device.

6. The ammonia-hydrogen internal combustion engine aftertreatment system with H2-SCR and NH3-SCR dual parallel circuits as described in claim 5, characterized in that, Also includes: The controller is electrically connected to the ammonia nozzle, the hydrogen nozzle, the first electric butterfly valve, the second electric butterfly valve, the third electric butterfly valve, and the fourth electric butterfly valve, respectively.

7. A control method for an aftertreatment system of an ammonia-hydrogen internal combustion engine with H2-SCR and NH3-SCR operating in parallel, used to control the treatment system as described in any one of claims 1-6, comprising: Real-time monitoring of the exhaust temperature T of the ammonia-hydrogen internal combustion engine; When T < 250℃, the inlet end of the second catalytic reaction branch is connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine, and the outlet end is connected to the anti-escape treatment device; the inlet and outlet ends of the first catalytic reaction branch are closed. When 250℃≤T<400℃, the inlet end of the first catalytic reaction branch and the inlet end of the second catalytic reaction branch are simultaneously connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine, and the outlet end of the first catalytic reaction branch and the outlet end of the second catalytic reaction branch are simultaneously connected to the escape prevention treatment device. When T≥400℃, the inlet end of the first catalytic reaction branch is connected to the exhaust pipe of the ammonia-hydrogen internal combustion engine, and the outlet end is connected to the anti-escape treatment device; the inlet and outlet ends of the second catalytic reaction branch are closed.

8. The control method for the aftertreatment system of an ammonia-hydrogen internal combustion engine with H2-SCR and NH3-SCR in parallel as described in claim 7, characterized in that, Also includes: When the first catalytic reaction branch is turned on, the outlet gas temperature t1 of the first electrically heated catalyst is monitored in real time. When t1 < 250℃, start the first electrically heated catalyst until t1 rises to 300℃; When the second catalytic reaction branch is turned on, the outlet gas temperature t2 of the second electrically heated catalyst is monitored in real time. When t2 < 150℃, start the second electrically heated catalyst until t2 rises to 200℃.

9. The control method for the aftertreatment system of an ammonia-hydrogen internal combustion engine with H2-SCR and NH3-SCR in parallel as described in claim 8, characterized in that, Also includes: Real-time monitoring of hydrogen concentration in the exhaust pipe of an ammonia-hydrogen internal combustion engine ammonia concentration and nitrogen oxide concentration When the first catalytic reaction branch is activated, and At that time, ammonia gas is injected into the ammonia selective catalytic reduction unit; When the second catalytic reaction branch is activated, and At that time, hydrogen is injected into the hydrogen selective catalytic reduction unit.

10. The control method for the aftertreatment system of an ammonia-hydrogen internal combustion engine with H2-SCR and NH3-SCR dual-path parallel operation according to claim 9, characterized in that, Also includes: Real-time monitoring of ammonia concentration at the outlet of the first catalytic reaction branch, hydrogen concentration at the outlet of the second catalytic reaction branch, and nitrogen oxide concentration at the inlet of the escape prevention treatment device; The amount of ammonia and hydrogen injected is adjusted based on the ammonia concentration at the outlet of the first catalytic reaction branch, the hydrogen concentration at the outlet of the second catalytic reaction branch, and the nitrogen oxide concentration at the inlet of the escape prevention treatment device.

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