Tight coupling H2-SCR ammonia / ammonia hydrogen internal combustion engine post-processing system and method

Abstract

The invention relates to a tight coupling H2-SCR ammonia / ammonia hydrogen internal combustion engine post-treatment system and method, the system comprises a first post-treatment device and a second post-treatment device which are sequentially connected to an exhaust pipe of an engine, and the first post-treatment device comprises a hydrogen selective catalytic reduction device; the second post-treatment device comprises an ammonia gas selective catalytic reducer, an ammonia escape catalyst and a nitrous oxide decomposition catalyst which are connected in sequence; fuel is combusted in a cylinder body of an engine, the fuel comprises ammonia fuel or ammonia-hydrogen mixed fuel, combustion waste gas contains ammonia gas, hydrogen, nitric oxide and nitrous oxide, the combustion waste gas flows out through an exhaust pipe and enters a system, and a detection device is arranged in the exhaust pipe to detect component concentration and exhaust temperature in the combustion waste gas respectively. And the ammonia gas is sprayed into the exhaust pipe. Compared with the prior art, the method aims at efficient reduction of pollutants discharged by the ammonia / ammonia hydrogen fuel internal combustion engine.

Description

Technical Field

[0001] The present invention belongs to the technical field of internal combustion engines, and relates to a tightly coupled H2-SCR ammonia / ammonia hydrogen internal combustion engine after-treatment system and method. Background Art

[0002] With the rapid development of industry in the past century, the level of human productivity has been greatly improved, but the resulting energy problems have also received increasing attention, including concerns about the depletion of fossil fuels and the negative impact of the greenhouse effect caused by carbon dioxide emissions on the environment. Therefore, in recent years, people have begun to work on the development of technologies that use carbon-neutral fuels, that is, the use of renewable energy. Ammonia (NH3), as a carbon-free fuel, has become a potential alternative energy source because it is rich in hydrogen (hydrogen content 17.75%, mass fraction) and liquid ammonia has a high energy density (11.5mJ / L). Ammonia can be mass-produced using hydrogen (H2) and nitrogen (N2) as raw materials through the Haber-Bosch process, so ammonia is also one of the world's most produced inorganic chemicals, and ammonia can also be produced through renewable energy sources such as wind power, solar energy, seawater temperature difference, etc. Since ammonia can be liquefied at room temperature (25°C) with only 1MPa pressure, its transportation and storage costs are significantly lower than hydrogen. Since ammonia has a higher octane number (>130), it can be used in engines with higher compression ratios. Therefore, there is great potential for applying ammonia, a new carbon-neutral fuel, to internal combustion engines.

[0003] However, ammonia faces many challenges as a fuel. The first is its weak reactivity, which is reflected in its slow flame burning speed (5-13 cm / s), narrow flammable range (15.5-27.0% volume ratio in air), and high ignition temperature (903K). Therefore, the mixed combustion of ammonia and other combustion promoters becomes possible. The most common is the combustion of ammonia and hydrogen as fuels. However, among the emissions produced by the combustion of ammonia / hydrogen fuels, nitrogen oxides (NO x ) and nitrous oxide (N2O) emissions are much higher than those of other traditional fuel combustion, and there are also unburned ammonia and hydrogen emissions. During the cold start phase, due to incomplete combustion, the emissions of ammonia and hydrogen are particularly serious, which can easily cause flashback in the exhaust duct. Therefore, compared with the after-treatment system of traditional fuel internal combustion engines, the working characteristics, temperature range, and selectivity of the reductant of the after-treatment system dedicated to ammonia / hydrogen internal combustion engines are very different. It is particularly necessary to develop a special after-treatment system for nitrogen oxides, nitrous oxide, hydrogen and ammonia.

[0004] Patent CN115111031A discloses a pollutant emission treatment system based on an ammonia hydrogen fuel power system. The pollutant-nitrogen oxide is accurately measured through the engine cylinder ion current sensor and multiple sensors outside the cylinder (first nitrogen oxide sensor, first temperature sensor, first ammonia sensor, second nitrogen oxide sensor, second temperature sensor and second ammonia sensor), and the post-treatment device is accurately controlled by the ammonia injection system to achieve the purpose of efficient reduction of emission pollutants; the amount of ammonia entering the ammonia cracker is controlled by various sensors inside and outside the cylinder to achieve optimal combustion in the cylinder and improve the pollutant composition in the exhaust from the source; the exhaust temperature is increased during the cold start phase through the electrically heated catalytic converter module and the ammonia oxidation catalyst module, which can effectively solve the problem of high ammonia and high nitrogen oxide emissions during cold start of ammonia combustion. However, the patent does not take into account the problem of hydrogen emissions in ammonia / ammonia hydrogen fuel engines, nor does it consider how to further use the emissions themselves to efficiently treat nitrogen oxides.

[0005] Patent CN117072287A discloses a pollutant emission post-treatment system and method for an ammonia / ammonia-hydrogen fuel internal combustion engine, wherein a catalytic device is provided on the exhaust pipe, and detection devices are provided before and after the catalytic device in the exhaust pipe, and the detection devices are connected to a controller; the catalytic device includes a three-in-one catalyst, which decomposes ammonia, nitrogen oxides and nitrous oxide in the exhaust gas; an ammonia injector is provided in the exhaust pipe in front of the three-in-one catalyst, and the ammonia injector is connected to an ammonia tank, and the ammonia tank is connected to a controller; detection devices are provided in the exhaust pipes before and after the three-in-one catalyst, and the detection devices include an ammonia sensor. Although the patent takes into account the problem of insufficient ignition temperature of post-treatment during the cold start stage, high-concentration hydrogen emissions are easily generated in ammonia / ammonia-hydrogen fuel engines during the cold start stage, and heating or flashback risks may occur during post-treatment. Summary of the invention

[0006] The purpose of the present invention is to overcome at least one defect of the above-mentioned prior art and to provide a tightly coupled H2-SCR ammonia / ammonia hydrogen internal combustion engine after-treatment system and method. The present invention is aimed at the efficient reduction of emission pollutants of ammonia / ammonia hydrogen fuel internal combustion engines.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] One of the technical solutions of the present invention is to provide an ammonia / ammonia-hydrogen internal combustion engine aftertreatment system with a tight coupling H2-SCR, the system comprising a first aftertreatment device and a second aftertreatment device connected in sequence to the exhaust pipe of the engine, the first aftertreatment device comprising a hydrogen selective catalytic reducer (H2-SCR), the second aftertreatment device comprising an ammonia selective catalytic reducer (NH3-SCR), an ammonia slip catalyst (ASC) and a nitrous oxide decomposition catalyst (DeN2O) connected in sequence;

[0009] The fuel is burned in the cylinder of the engine. The fuel includes ammonia fuel or ammonia-hydrogen mixed fuel. The combustion exhaust contains unburned ammonia (NH3) and hydrogen (H2) as well as a certain amount of nitrogen oxides (NO x ) and nitrous oxide (N2O), the combustion exhaust gas flows out through the exhaust pipe and enters the system. The exhaust pipe is equipped with a detection device to detect the concentration of components in the combustion exhaust gas and the exhaust temperature, and transmit the signal to the controller. The controller controls the ammonia in the ammonia fuel tank to be used as a reducing agent and is injected into the exhaust pipe through the ammonia injector.

[0010] The main reason for the emission of hydrogen in a pure ammonia fuel internal combustion engine is the presence of unburned ammonia. Ammonia will crack under high temperature conditions, and the cracking products are nitrogen (N2) and hydrogen. Therefore, the hydrogen emissions in a pure ammonia fuel internal combustion engine come from this. The hydrogen emissions in an ammonia-hydrogen fuel internal combustion engine mainly come from two sources, one is unburned hydrogen, and the other is the hydrogen produced by the high-temperature cracking of ammonia.

[0011] During the cold start phase and stable operation phase of the engine, there is unburned ammonia and unburned hydrogen in the combustion products of the ammonia / ammonia-hydrogen internal combustion engine. The hydrogen selective catalytic reducer is installed close to the exhaust end of the engine to make use of the exhaust temperature as much as possible to increase the ignition speed and catalytic temperature of the hydrogen selective catalytic reducer. While absorbing hydrogen, it uses hydrogen as a reducing agent to treat nitrogen oxides.

[0012] Furthermore, a detection device is installed in front of the first after-treatment device, and the detection device includes a nitrogen oxide sensor, a hydrogen sensor and a temperature sensor. The nitrogen oxide sensor and the hydrogen sensor measure the concentration of nitrogen oxides and hydrogen in the combustion exhaust gas here, and the temperature sensor measures the exhaust temperature here. The detection results of the nitrogen oxide sensor and the hydrogen sensor are used to infer whether the emission of nitrogen oxides can be efficiently processed in the hydrogen selective catalytic reducer. If it cannot be effectively processed, then the rear-end ammonia selective catalytic reducer needs to spray ammonia to further process the residual nitrogen oxides; the temperature sensor is used to detect the exhaust temperature at the engine end, so that it can be determined whether the exhaust temperature is within the optimal processing temperature of the hydrogen selective catalytic reducer. If not, it means that there will still be residual nitrogen oxides after the treatment of the hydrogen selective catalytic reducer, so the rear-end ammonia selective catalytic reducer needs to work.

[0013] As a preferred technical solution, a detection device is installed at the front section of the hydrogen selective catalytic reducer.

[0014] As a preferred technical solution, the catalyst of the hydrogen selective catalytic reducer is a precious metal catalyst.

[0015] As a preferred technical solution, the noble metal catalyst is a platinum-based catalyst.

[0016] As a preferred technical solution, the platinum-based catalyst includes Pt / H-ZSM-5, Pt / MgO-CeO2 or Pt / Zr-SiO2.

[0017] The ammonia selective catalytic reducer is mainly used to further reduce the residual nitrogen oxides after being treated by the hydrogen selective catalytic reducer; after the engine is warmed up, the concentration of nitrogen oxides emitted increases, at this time the ammonia selective catalytic reducer will become the main device for treating nitrogen oxides.

[0018] Furthermore, a detection device is installed before the second after-treatment device, and the detection device includes a temperature sensor and a nitrogen oxide sensor. Before ammonia is injected into the second after-treatment device through the ammonia injector, the temperature sensor measures the exhaust temperature here, and the nitrogen oxide sensor measures the nitrogen oxide concentration in the combustion exhaust gas here. The temperature sensor is used to detect whether the exhaust temperature is at a suitable treatment temperature after passing through the hydrogen selective catalytic reducer, so as to control the replenishment amount of the reducing agent ammonia in real time. The nitrogen oxide sensor is mainly used to monitor the residual concentration of nitrogen oxides after the hydrogen selective catalytic reducer, so as to determine whether the reducing agent ammonia needs to be replenished in the ammonia selective catalytic reducer. If the concentration of nitrogen oxides is low, the additional ammonia injected is reduced. If the residual nitrogen oxides are high, more ammonia needs to be replenished.

[0019] As a preferred technical solution, a detection device is installed in the front section of the ammonia selective catalytic reducer.

[0020] Furthermore, the temperature sensor and the nitrogen oxide sensor feed back signals to the controller, which controls the ammonia in the ammonia fuel tank to be injected into the second after-treatment device through the ammonia injector. The controller controls the ammonia injector in real time to provide the reducing agent for the second after-treatment device to ensure that the ammonia and nitrogen oxides in the ammonia selective catalytic reducer can fully react.

[0021] As a preferred technical solution, in order to ensure the processing efficiency of the ammonia selective catalytic reduction device under the condition of lower exhaust temperature, it is necessary to use a selective catalytic reduction catalyst with good low-temperature processing performance. The catalyst of the ammonia selective catalytic reduction device uses a molecular sieve catalyst.

[0022] As a preferred technical solution, the molecular sieve catalyst includes a copper-based molecular sieve catalyst, an iron-based molecular sieve catalyst or a manganese-based molecular sieve catalyst.

[0023] Due to the slight toxicity of ammonia and the possibility of ammonia leakage, an ammonia slip catalyst is installed after the ammonia selective catalytic reducer to meet the 10×10 -6 ppm ammonia leakage requirement.

[0024] As a preferred technical solution, the catalyst of the ammonia slip catalyst includes a precious metal alloy or a precious metal oxide.

[0025] As a preferred technical solution, the precious metal alloy is a silver-copper alloy.

[0026] As a preferred technical solution, the noble metal oxide includes platinum oxide, palladium oxide or rhodium oxide.

[0027] A nitrous oxide decomposition catalyst is installed after the ammonia slip catalyst to treat nitrous oxide generated from the hydrogen selective catalytic reducer and ammonia selective catalytic reducer as well as the engine combustion process.

[0028] Furthermore, a detection device is installed after the second post-treatment device, and the detection device includes a nitrogen oxide sensor, which measures the concentration of nitrogen oxides in the combustion exhaust gas here. The nitrogen oxide sensor is mainly used to detect whether there are any residual nitrogen oxides after the previous series of treatments, and is used to feed back to the controller to adjust the amount of ammonia injected into the ammonia selective catalytic reducer.

[0029] As a preferred technical solution, a detection device is installed at the rear section of the nitrous oxide decomposition catalyst.

[0030] As a preferred technical solution, the catalyst of the nitrous oxide decomposition catalyst is a metal catalyst.

[0031] As a preferred technical solution, the metal catalyst includes copper, iron, nickel, indium, palladium, ruthenium or rhodium.

[0032] As a preferred technical solution, the catalyst of the nitrous oxide decomposition catalyst is a precious metal catalyst.

[0033] As a preferred technical solution, the noble metal catalyst includes palladium, ruthenium or rhodium.

[0034] Furthermore, the second after-treatment device also includes an electrically heated catalyst (EHC), which is installed in front of the ammonia slip catalyst and is mainly used for heating in the cold start phase to heat the exhaust temperature to above 200°C; usually the electrically heated catalyst performs high-temperature oxidation on some components in the exhaust gas, that is, the electrically heated catalyst plays a role similar to the diesel oxidation catalyst (DOC) in the diesel engine after-treatment system in addition to heating.

[0035] As a preferred technical solution, the structure of the electric heating catalyst adopts a honeycomb structure, the inner filler adopts a ceramic material, and then the catalyst is plated on the inner filler.

[0036] As a preferred technical solution, the ceramic material is silicon carbide.

[0037] As a preferred technical solution, the catalyst of the electrically heated catalyst unit is a precious metal catalyst.

[0038] As a preferred technical solution, the noble metal catalyst includes platinum or palladium.

[0039] As a preferred technical solution, the electrically heated catalyst is driven by a vehicle-mounted battery.

[0040] Furthermore, in order to compensate for the problem of insufficient reaction temperature of the ammonia slip catalyst, an electric heating catalyst is installed after the ammonia selective catalytic reducer and before the ammonia slip catalyst for heating to ensure that the ammonia slip catalyst can react effectively.

[0041] Furthermore, in order to compensate for the problem of insufficient reaction temperature of the ammonia selective catalytic reducer, an electric heating catalyst is installed in front of the ammonia selective catalytic reducer for heating, ensuring that both the ammonia selective catalytic reducer and the ammonia slip catalyst can react effectively.

[0042] Furthermore, the system further comprises a third after-treatment device, wherein the third after-treatment device comprises a particulate filter (PF), and the particulate filter is installed after the second after-treatment device to capture particulate matter generated during the operation of the engine.

[0043] As a preferred technical solution, a particulate filter is installed at the rear section of the nitrous oxide decomposition catalyst.

[0044] As a preferred technical solution, the particle filter adopts a ceramic filter to adsorb carbon particles on the filter to achieve the effect of capturing particles.

[0045] One of the technical solutions of the present invention is to provide a method for post-treatment of an ammonia / ammonia-hydrogen internal combustion engine with a tightly coupled H2-SCR, the method using the system to post-treat the exhaust gas of the ammonia / ammonia-hydrogen internal combustion engine, the method comprising the following steps:

[0046] After the combustion exhaust gas passes through the nitrogen oxide sensor, hydrogen sensor and temperature sensor to detect the concentration and temperature, it passes through the hydrogen selective catalytic reducer for the reaction of nitrogen oxides and hydrogen, passes through the temperature sensor and nitrogen oxide sensor to detect the temperature and concentration, and is injected with ammonia through the ammonia injector. It then passes through the ammonia selective catalytic reducer for the reaction of nitrogen oxides and ammonia, passes through the ammonia escape catalyst to deal with ammonia escape, passes through the nitrous oxide decomposition catalyst to deal with nitrous oxide, and passes through the nitrogen oxide sensor to detect the concentration, so as to achieve post-treatment emission standards.

[0047] As a preferred technical solution, before the ammonia slip is processed by the ammonia slip catalyst, it is heated by an electric heating catalyst.

[0048] As a preferred technical solution, before the nitrogen oxides and ammonia react in an ammonia selective catalytic reducer, they are heated in an electric heating catalyst.

[0049] As a preferred technical solution, after the concentration is detected by the nitrogen oxide sensor, the particles are captured by the particulate filter.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) Based on the emission characteristics of ammonia-hydrogen fuel internal combustion engines, the present invention proposes and designs a special aftertreatment system for ammonia / ammonia-hydrogen fuel internal combustion engines, which combines a hydrogen selective catalytic reducer, an ammonia selective catalytic reducer, an electric heating catalyst, an ammonia slip catalyst and a nitrous oxide decomposition catalyst to achieve the purpose of efficient reduction of emission pollutants;

[0052] (2) The hydrogen selective catalytic reducer in the present invention not only processes the hydrogen emissions of the engine, but also uses hydrogen as a reducing agent to process nitrogen oxides. Since nitrogen oxides can be efficiently processed under the condition of exhaust temperature below 200°C, the engine is guaranteed to have a high nitrogen oxide processing capacity during the cold start stage. Compared with the tightly coupled selective catalytic reducer using ammonia as a reducing agent, the hydrogen selective catalytic reducer can directly use hydrogen as a reducing agent, thus solving the problem of hydrogen emissions. Compared with the electrically heated catalyst, no additional heating is required during the cold start stage, and a higher post-processing efficiency can be obtained.

[0053] (3) The hydrogen selective catalytic reducer in the present invention is installed near the exhaust side to form a close-coupled selective catalytic reducer, firstly to obtain a higher ignition temperature during the cold start phase and better handle the emissions of hydrogen and nitrogen oxides during the cold start phase; secondly to ensure that the emitted hydrogen can be processed earlier to prevent hydrogen from flowing into the downstream exhaust duct and causing flashback;

[0054] (4) The present invention installs a nitrogen oxide sensor, a hydrogen sensor and a temperature sensor at the front section of the hydrogen selective catalytic reducer to detect the nitrogen oxide concentration, hydrogen concentration and exhaust temperature. The detection results of the nitrogen oxide sensor and the hydrogen sensor can be used to infer whether the nitrogen oxide emission can be efficiently processed in the hydrogen selective catalytic reducer. If it cannot be effectively processed, then the rear ammonia selective catalytic reducer needs to inject ammonia to further process the residual nitrogen oxides; the temperature sensor is used to detect the exhaust temperature at the engine end, so that it can be determined whether the exhaust temperature is within the optimal processing temperature of the hydrogen selective catalytic reducer. If not, it means that there will still be nitrogen oxides remaining after the hydrogen selective catalytic reducer is processed, and then the rear ammonia selective catalytic reducer needs to work;

[0055] (5) The present invention installs a temperature sensor and a nitrogen oxide sensor in the front section of the ammonia selective catalytic reducer to detect the exhaust temperature and nitrogen oxide concentration. When the temperature reaches the ignition temperature of the ammonia selective catalytic reducer, or when there are still residual nitrogen oxides that need to be treated, the ammonia injector starts to inject ammonia to promote the ammonia selective catalytic reducer to treat nitrogen oxide emissions. This method can effectively reduce the injection of ammonia, save ammonia fuel, and effectively reduce the ammonia escape concentration. An electric heating catalyst can be selectively added before the ammonia selective catalytic reducer to increase the exhaust temperature, and the exhaust temperature is heated to above 200°C, thereby improving the treatment efficiency of the ammonia selective catalytic reducer for nitrogen oxides during cold start.

[0056] (6) The present invention uses multiple hydrogen / ammonia / nitrogen oxide sensors installed in the exhaust system to accurately measure the combustion pollutants and reflect them to the controller. The controller is connected to the ammonia fuel tank to control the ammonia injector to accurately control the injection amount of the reducing agent in the ammonia selective catalytic reducer, thereby detecting the content of exhaust pollutants, controlling the reaction conditions and avoiding the introduction of more pollutants.

[0057] (7) The ammonia slip catalyst in the present invention is the main device for preventing ammonia slip; an electric heating catalyst can be selectively added before the ammonia slip catalyst to increase the exhaust temperature, heating the exhaust temperature to above 200° C., thereby improving the efficiency of the ammonia slip catalyst in treating ammonia slip during cold start;

[0058] (8) The nitrous oxide decomposition catalyst of the present invention is used to treat nitrous oxide emissions generated during hydrogen selective catalytic reduction, ammonia selective catalytic reduction and engine combustion;

[0059] (9) The present invention installs a nitrogen oxide sensor at the rear section of the nitrous oxide decomposition catalyst to detect the concentration of nitrogen oxides in the final combustion exhaust gas and assist in determining the result of post-treatment. The main purpose is to detect whether nitrogen oxides are still residual after a series of previous treatments, so as to feedback and adjust the amount of ammonia injected into the ammonia selective catalytic reducer;

[0060] (10) In the present invention, an additional particulate matter filter can be selected to capture particulate matter in the combustion products of an ammonia / ammonia-hydrogen fuel internal combustion engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 This is a schematic diagram of the structure of the ammonia / ammonia-hydrogen internal combustion engine aftertreatment system tightly coupled with H2-SCR in Example 1 of the present invention;

[0062] Figure 2 This is a schematic diagram of the structure of the ammonia / ammonia-hydrogen internal combustion engine aftertreatment system tightly coupled with H2-SCR in Example 2 of the present invention;

[0063] Figure 3 This is a schematic diagram of the structure of the ammonia / ammonia-hydrogen internal combustion engine aftertreatment system tightly coupled with H2-SCR in Example 3 of the present invention;

[0064] Figure 4 This is a schematic diagram of the structure of the ammonia / ammonia-hydrogen internal combustion engine aftertreatment system tightly coupled with H2-SCR in Example 4 of the present invention;

[0065] Figure 5 This is a schematic diagram of the structure of the ammonia / ammonia-hydrogen internal combustion engine aftertreatment system tightly coupled with H2-SCR in Example 5 of the present invention;

[0066] Figure 6Schematic diagram of the structure of the ammonia / ammonia-hydrogen internal combustion engine after-treatment system with tightly coupled H2-SCR in Example 6 of the present invention.

[0067] Description of the markings in the figure:

[0068] 1—nitrous oxide decomposition catalyst, 2—ammonia injector, 4—temperature sensor, 5—nitrogen oxide sensor, 6—controller, 7—engine, 8—ammonia fuel tank, 9—hydrogen selective catalytic reducer, 10—ammonia selective catalytic reducer, 11—ammonia escape catalyst, 12—electrically heated catalyst, 13—particulate matter filter, 14—hydrogen sensor. DETAILED DESCRIPTION

[0069] The present invention is described in detail below in conjunction with specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0070] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", "third", etc. are used to describe common objects, which only refer to different instances of the same object, and are not intended to imply that the objects described in this way must adopt a given order, whether in time, space, order or any other way.

[0071] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0072] Embodiment 1:

[0073] A tightly coupled H2-SCR ammonia / ammonia hydrogen internal combustion engine aftertreatment system, such as Figure 1As shown, it includes a first after-treatment device and a second after-treatment device connected in sequence to the exhaust pipe of the engine 7, the first after-treatment device includes a hydrogen selective catalytic reducer (H2-SCR) 9, and the second after-treatment device includes an ammonia selective catalytic reducer (NH3-SCR) 10, an ammonia slip catalyst (ASC) 11 and a nitrous oxide decomposition catalyst (DeN2O) 1 connected in sequence;

[0074] The fuel is burned in the cylinder of the engine 7. The fuel includes ammonia fuel or ammonia-hydrogen mixed fuel. In this embodiment, ammonia-hydrogen mixed fuel is preferred. The combustion exhaust gas contains unburned ammonia (NH3) and hydrogen (H2) as well as a certain amount of nitrogen oxides (NO x ) and nitrous oxide (N2O), the combustion exhaust gas flows out through the exhaust pipe and enters the system, the exhaust pipe is provided with a detection device to detect the concentration of components in the combustion exhaust gas and the exhaust temperature, and transmit the signal to the controller 6, the controller 6 controls the ammonia in the ammonia fuel tank 8 as a reducing agent to be injected into the exhaust pipe through the ammonia injector 2;

[0075] The main reason for the emission of hydrogen in pure ammonia fuel internal combustion engines is the presence of unburned ammonia. Ammonia will crack under high temperature conditions, and the cracking products are nitrogen (N2) and hydrogen. Therefore, the hydrogen emission in pure ammonia fuel internal combustion engines comes from this. The hydrogen emission in ammonia-hydrogen fuel internal combustion engines mainly comes from two sources, one is unburned hydrogen, and the other is hydrogen produced by high-temperature cracking of ammonia.

[0076] During the cold start and stable operation of the engine 7, there are unburned ammonia and unburned hydrogen in the combustion products of the ammonia / ammonia-hydrogen internal combustion engine. The hydrogen selective catalytic reducer 9 is installed near the exhaust end of the engine 7, and the exhaust temperature is used as much as possible to increase the ignition speed and catalytic temperature of the hydrogen selective catalytic reducer 9. While absorbing hydrogen, the nitrogen oxides are treated with hydrogen as a reducing agent.

[0077] A detection device, namely, a nitrogen oxide sensor 5, a hydrogen sensor 14 and a temperature sensor 4, is installed before the first post-treatment device, i.e., the front section of the hydrogen selective catalytic reducer 9. The nitrogen oxide sensor 5 and the hydrogen sensor 14 measure the concentration of nitrogen oxides and hydrogen in the combustion exhaust gas here, and the temperature sensor 4 measures the exhaust temperature here. The detection results of the nitrogen oxide sensor 5 and the hydrogen sensor 14 can be used to infer whether the emission of nitrogen oxides can be efficiently processed in the hydrogen selective catalytic reducer 9. If it cannot be effectively processed, then the rear ammonia selective catalytic reducer 10 needs to inject ammonia to further process the residual nitrogen oxides; the temperature sensor 14 is used to detect the exhaust temperature at the engine end, so that it can be determined whether the exhaust temperature is within the optimal processing temperature of the hydrogen selective catalytic reducer 9. If not, it means that there will still be nitrogen oxides remaining after the hydrogen selective catalytic reducer 9 is processed, so the rear ammonia selective catalytic reducer 10 needs to work;

[0078] The catalyst of the hydrogen selective catalytic reducer 9 is usually a precious metal catalyst, with platinum-based catalyst being the most important, such as Pt / H-ZSM-5, Pt / MgO-CeO2 or Pt / Zr-SiO2, and preferably Pt / MgO-CeO2 in this embodiment;

[0079] The ammonia selective catalytic reducer 10 is mainly used to further reduce the residual nitrogen oxides after being treated by the hydrogen selective catalytic reducer 9; after the engine 7 is warmed up, the concentration of the emitted nitrogen oxides increases, and at this time the ammonia selective catalytic reducer 10 will become the main device for treating the nitrogen oxides;

[0080] A detection device, namely, a temperature sensor 4 and a nitrogen oxide sensor 5, is installed in front of the second post-treatment device, that is, the front section of the ammonia selective catalytic reducer 10. The temperature sensor 4 and the nitrogen oxide sensor 5 feedback signals to the controller 6. The controller 6 controls the ammonia in the ammonia fuel tank 8 to be injected into the front section of the ammonia selective catalytic reducer 10 through the ammonia injector 2. In this embodiment, the ammonia injector 2 is preferably an ammonia gas nozzle. The temperature sensor 4 measures the exhaust temperature here, and the nitrogen oxide sensor 5 measures the nitrogen oxide concentration in the combustion exhaust gas here. The temperature sensor 4 is used to detect the exhaust gas after passing through the hydrogen selective catalytic reducer 9. Whether the temperature is at a suitable processing temperature, so as to control the amount of ammonia gas added as a reducing agent in real time. The nitrogen oxide sensor 5 is mainly used to monitor the residual concentration of nitrogen oxides after the hydrogen selective catalytic reducer 9, so as to determine whether the ammonia gas selective catalytic reducer 10 needs to be supplemented with ammonia gas as a reducing agent. If the concentration of nitrogen oxides is low, the amount of additional ammonia gas injected is reduced. If the residual nitrogen oxides are high, more ammonia gas needs to be supplemented. The controller 6 controls the ammonia gas injector 2 in real time to provide a reducing agent for the second post-processing device, so as to ensure that ammonia gas and nitrogen oxides in the ammonia selective catalytic reducer 10 can fully react.

[0081] In order to ensure the processing efficiency of the ammonia selective catalytic reduction device 10 under the condition of relatively low exhaust temperature, it is necessary to use a selective catalytic reduction catalyst with good low-temperature processing performance. The catalyst of the ammonia selective catalytic reduction device 10 generally uses a molecular sieve catalyst, such as a copper-based molecular sieve catalyst, an iron-based molecular sieve catalyst or a manganese-based molecular sieve catalyst. In this embodiment, an iron-based molecular sieve catalyst is preferably used;

[0082] Due to the slight toxicity of ammonia and the possibility of ammonia leakage, an ammonia slip catalyst 11 is installed after the ammonia selective catalytic reducer 10 to meet the 10×10 -6 ppm ammonia leakage requirement;

[0083] The catalyst of the ammonia slip catalyst 11 is generally a noble metal alloy, such as a silver-copper alloy, or a noble metal oxide, such as platinum oxide, palladium oxide or rhodium oxide, and in this embodiment, platinum oxide is preferred;

[0084] A nitrous oxide decomposition catalyst 1 is installed after the ammonia slip catalyst 11 to treat nitrous oxide generated from the hydrogen selective catalytic reducer 9 and the ammonia selective catalytic reducer 10 as well as the combustion process of the engine 7;

[0085] A detection device, namely, a nitrogen oxide sensor 5, is installed after the second post-treatment device, i.e., the rear section of the nitrous oxide decomposition catalyst 1. The nitrogen oxide sensor 5 measures the nitrogen oxide concentration in the combustion exhaust gas here. The nitrogen oxide sensor 5 is mainly used to detect whether there is any residual nitrogen oxide after the previous series of treatments, and is used to feed back to the controller 6 to adjust the amount of ammonia injected into the ammonia selective catalytic reduction device 10;

[0086] The catalyst of the nitrous oxide decomposition catalyst 1 is generally a metal catalyst, such as copper, iron, nickel, indium, palladium, ruthenium or rhodium. The effect of precious metal catalysts is better, such as palladium, ruthenium or rhodium. In this embodiment, palladium is preferred.

[0087] A method for post-treatment of an ammonia / ammonia-hydrogen internal combustion engine based on H2-SCR, using the above system to post-treat the exhaust gas of an ammonia / ammonia-hydrogen internal combustion engine, the specific steps are as follows:

[0088] After the combustion exhaust gas passes through the nitrogen oxide sensor 5, the hydrogen sensor 14 and the temperature sensor 4 to detect the concentration and temperature, it passes through the hydrogen selective catalytic reducer 9 to react with nitrogen oxides and hydrogen, and after the temperature sensor 4 and the nitrogen oxide sensor 5 detect the temperature and concentration and ammonia is sprayed into the ammonia injector 2, it passes through the ammonia selective catalytic reducer 10 to react with nitrogen oxides and ammonia, passes through the ammonia slip catalyst 11 to treat ammonia slip, passes through the nitrous oxide decomposition catalyst 1 to treat nitrous oxide, and passes through the nitrogen oxide sensor 5 to detect the concentration, so as to achieve post-treatment emission standards.

[0089] The following embodiments add new components.

[0090] The second post-treatment device also includes an electrically heated catalyst (EHC) 12, which is installed in front of the ammonia slip catalyst 11 and is mainly used for heating in the cold start stage to heat the exhaust gas temperature to above 200°C; generally, the electrically heated catalyst 12 can perform high-temperature oxidation on some components in the exhaust gas, that is, the electrically heated catalyst 12 plays a role similar to that of a diesel oxidation catalyst (DOC) in a diesel engine post-treatment system in addition to heating;

[0091] The structure of the electric heating catalyst 12 generally adopts a honeycomb structure, and the inner filler adopts a ceramic material, such as silicon carbide, and then a catalyst is plated on the inner filler. The catalyst generally adopts a precious metal catalyst, such as platinum or palladium, and platinum is preferably used in this embodiment;

[0092] The electrically heated catalyst 12 may be driven by a vehicle battery.

[0093] Embodiment 2:

[0094] A tightly coupled H2-SCR ammonia / ammonia hydrogen internal combustion engine aftertreatment system, such as Figure 2 As shown, it is basically the same as Example 1, except that, in order to compensate for the problem of insufficient reaction temperature of the ammonia slip catalyst 11, an electric heating catalyst 12 is installed after the ammonia selective catalytic reduction device 10 and before the ammonia slip catalyst 11 for heating, so as to ensure that the ammonia slip catalyst 11 can react effectively.

[0095] A method for after-treatment of an ammonia / ammonia-hydrogen internal combustion engine with a tightly coupled H2-SCR, using the above system to after-treat the exhaust gas from the combustion of an ammonia / ammonia-hydrogen internal combustion engine, is basically the same as Example 1, except that before the ammonia slip is treated through the ammonia slip catalyst 11, it is heated through the electric heating catalyst 12.

[0096] Embodiment 3:

[0097] A tightly coupled H2-SCR ammonia / ammonia hydrogen internal combustion engine aftertreatment system, such as Figure 3 As shown, it is basically the same as Example 1, except that, in order to compensate for the problem of insufficient reaction temperature of the ammonia selective catalytic reducer 10, an electric heating catalyst 12 is installed in front of the ammonia selective catalytic reducer 10 for heating, ensuring that both the ammonia selective catalytic reducer 10 and the ammonia slip catalyst 11 can react effectively.

[0098] A method for after-treatment of an ammonia / ammonia-hydrogen internal combustion engine with a tightly coupled H2-SCR, using the above system to after-treat the exhaust gas from the combustion of an ammonia / ammonia-hydrogen internal combustion engine, is basically the same as Example 1, except that before the nitrogen oxides and ammonia react in the ammonia selective catalytic reducer 10, they are heated by an electrically heated catalyst 12.

[0099] The following embodiments add new components.

[0100] The system further includes a third post-processing device, which includes a particulate filter (PF) 13, which is installed after the second post-processing device, that is, after the nitrous oxide decomposition catalyst 1, to capture particulate matter generated during the operation of the engine 7;

[0101] The particle filter 13 is usually a ceramic filter, which adsorbs carbon particles on the filter to achieve the effect of capturing particles.

[0102] Embodiment 4:

[0103] A tightly coupled H2-SCR ammonia / ammonia hydrogen internal combustion engine aftertreatment system, such as Figure 4 As shown, it is basically the same as the embodiment 1, except that a particulate filter 13 is installed at the rear stage of the nitrous oxide decomposition catalyst 1.

[0104] A method for after-treatment of an ammonia / ammonia-hydrogen internal combustion engine with a tightly coupled H2-SCR uses the above system to after-treat the exhaust gas from the combustion of an ammonia / ammonia-hydrogen internal combustion engine, which is basically the same as Example 1, except that after the concentration is detected by the nitrogen oxide sensor 5, particles are captured by the particulate filter 13.

[0105] Embodiment 5:

[0106] A tightly coupled H2-SCR ammonia / ammonia hydrogen internal combustion engine aftertreatment system, such as Figure 5 As shown, it is basically the same as the embodiment 2, except that a particulate filter 13 is installed at the rear stage of the nitrous oxide decomposition catalyst 1.

[0107] A method for after-treatment of an ammonia / ammonia-hydrogen internal combustion engine with a tightly coupled H2-SCR uses the above system to after-treat the exhaust gas from the combustion of an ammonia / ammonia-hydrogen internal combustion engine, which is basically the same as Example 2, except that after the concentration is detected by the nitrogen oxide sensor 5, particles are captured by the particulate filter 13.

[0108] Embodiment 6:

[0109] A tightly coupled H2-SCR ammonia / ammonia hydrogen internal combustion engine aftertreatment system, such as Figure 6 As shown, it is basically the same as the embodiment 3, except that a particulate filter 13 is installed at the rear section of the nitrous oxide decomposition catalyst 1.

[0110] A method for after-treatment of an ammonia / ammonia-hydrogen internal combustion engine with a tightly coupled H2-SCR uses the above system to after-treat the exhaust gas from the combustion of an ammonia / ammonia-hydrogen internal combustion engine, which is basically the same as Example 3, except that after the concentration is detected by the nitrogen oxide sensor 5, the particles are captured by the particulate filter 13.

[0111] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A tightly coupled H2-SCR ammonia / ammonia hydrogen internal combustion engine aftertreatment system, characterized in that: The system comprises a first after-treatment device and a second after-treatment device connected in sequence to an exhaust pipe of an engine (7), wherein the first after-treatment device comprises a hydrogen selective catalytic reducer (9), and the second after-treatment device comprises an ammonia selective catalytic reducer (10), an ammonia slip catalyst (11) and a nitrous oxide decomposition catalyst (1) connected in sequence; The fuel is burned in the cylinder of the engine (7), the fuel comprising ammonia fuel or ammonia-hydrogen mixed fuel, the combustion exhaust gas contains ammonia and hydrogen as well as nitrogen oxides and nitrous oxide, the combustion exhaust gas flows out through an exhaust pipe and enters the system, a detection device is arranged in the exhaust pipe to respectively detect the concentration of components in the combustion exhaust gas and the exhaust temperature, and the ammonia is injected into the exhaust pipe.

2. The tightly coupled H2-SCR ammonia / ammonia-hydrogen internal combustion engine aftertreatment system according to claim 1, characterized in that: A detection device is installed in front of the first post-processing device, and the detection device comprises a nitrogen oxide sensor (5), a hydrogen sensor (14) and a temperature sensor (4).

3. The tightly coupled H2-SCR ammonia / ammonia-hydrogen internal combustion engine aftertreatment system according to claim 1, characterized in that: A detection device is installed in front of the second post-processing device, the detection device comprising a temperature sensor (4) and a nitrogen oxide sensor (5), and ammonia is injected into the front of the second post-processing device through an ammonia injector (2).

4. The tightly coupled H2-SCR ammonia / ammonia-hydrogen internal combustion engine aftertreatment system according to claim 3, characterized in that: The temperature sensor (4) and the nitrogen oxide sensor (5) feed back signals to a controller (6), and the controller (6) controls the ammonia in the ammonia fuel tank (8) to be injected into the front of the second post-treatment device through the ammonia injector (2).

5. The tightly coupled H2-SCR ammonia / ammonia-hydrogen internal combustion engine aftertreatment system according to claim 1, characterized in that: A detection device is installed after the second post-processing device, and the detection device includes a nitrogen oxide sensor (5).

6. The tightly coupled H2-SCR ammonia / ammonia-hydrogen internal combustion engine aftertreatment system according to claim 1, characterized in that: The second post-treatment device also includes an electrically heated catalyst (12), which is installed before the ammonia slip catalyst (11).

7. The tightly coupled H2-SCR ammonia / ammonia-hydrogen internal combustion engine aftertreatment system according to claim 6, characterized in that: An electric heating catalyst (12) is installed after the ammonia selective catalytic reducer (10) and before the ammonia slip catalyst (11).

8. The tightly coupled H2-SCR ammonia / ammonia-hydrogen internal combustion engine aftertreatment system according to claim 6, characterized in that: An electric heating catalyst (12) is installed before the ammonia selective catalytic reducer (10).

9. The tightly coupled H2-SCR ammonia / ammonia-hydrogen internal combustion engine aftertreatment system according to claim 1, characterized in that: The system further comprises a third post-processing device, the third post-processing device comprising a particulate filter (13), and the particulate filter (13) is installed after the second post-processing device.

10. A method for post-treatment of an ammonia / ammonia-hydrogen internal combustion engine with a tightly coupled H2-SCR, characterized in that: The method uses the system according to any one of claims 1 to 9 to perform post-treatment of ammonia / ammonia-hydrogen internal combustion engine combustion exhaust gas, and the method comprises the following steps: After the combustion exhaust gas passes through the nitrogen oxide sensor (5), the hydrogen sensor (14) and the temperature sensor (4) to detect the concentration and temperature, it passes through the hydrogen selective catalytic reducer (9) to react the nitrogen oxide and hydrogen, passes through the temperature sensor (4) and the nitrogen oxide sensor (5) to detect the temperature and concentration, and passes through the ammonia injector (2) to inject ammonia, passes through the ammonia selective catalytic reducer (10) to react the nitrogen oxide and ammonia, passes through the ammonia slip catalyst (11) to treat the ammonia slip, passes through the nitrous oxide decomposition catalyst (1) to treat the nitrous oxide, and passes through the nitrogen oxide sensor (5) to detect the concentration, so as to achieve post-treatment emission standards.

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