Hydrogen fuel engine exhaust after-treatment system and method

Abstract

The present application provides a hydrogen fuel engine exhaust after-treatment system and method, the system comprising: an exhaust pipeline, including an intake main pipeline, a first parallel pipeline, a second parallel pipeline and an outlet main pipeline, wherein the air inlet of the intake main pipeline is connected to the air outlet of the hydrogen fuel engine; a temperature sensor, arranged in the intake main pipeline; a three-way valve, wherein the air inlet of the three-way valve is connected to the air outlet of the intake main pipeline, the first air outlet of the three-way valve is connected to the air inlet of the first parallel pipeline, and the second air outlet of the three-way valve is connected to the air inlet of the second parallel pipeline; a hydrogen-oxygen catalyst, arranged in the first parallel pipeline; an ammonia selective catalytic reduction device, arranged in the first parallel pipeline, downstream of the hydrogen-oxygen catalyst; and a hydrogen selective catalytic reduction device, arranged in the second parallel pipeline. Through the present application, a reasonable selection of exhaust after-treatment methods is made based on the original exhaust temperature of the hydrogen fuel engine, thereby effectively suppressing nitrogen oxide and hydrogen emissions under all operating conditions.

Description

Technical Field

[0001] The present application relates to the technical field of exhaust gas aftertreatment, and in particular to a system and method for exhaust gas aftertreatment of a hydrogen fuel engine. Background Art

[0002] As a clean energy technology, hydrogen fuel engine has relatively few pollutants in its exhaust gas, but they still exist. The main pollutants are nitrogen oxides (NO x ) This is because during the hydrogen fuel combustion process, due to the high temperature conditions, a certain amount of nitrogen oxides, including nitric oxide (NO) and nitrogen dioxide (NO2), may be produced. In addition, the exhaust gas emitted by hydrogen fuel engines may also contain unburned hydrogen. Although relevant regulations do not impose emission control requirements for hydrogen as a pollutant, hydrogen is a flammable and explosive gas and should be removed from the exhaust gas as much as possible for safety reasons.

[0003] Currently, there are two main technology approaches for engine exhaust aftertreatment: NH3-SCR, which removes nitrogen oxides from exhaust gas through an ammonia selective catalytic reduction device; and H2-SCR, which removes nitrogen oxides from exhaust gas through a hydrogen selective catalytic reduction device. However, when applied to hydrogen-fueled engines, neither of these technology approaches can effectively suppress nitrogen oxide and hydrogen emissions under all operating conditions. Summary of the Invention

[0004] The present application provides a hydrogen fuel engine exhaust after-treatment system and method, which can solve the technical problem in the prior art of being unable to effectively suppress nitrogen oxide and hydrogen emissions under all operating conditions.

[0005] In a first aspect, an embodiment of the present application provides a hydrogen fuel engine exhaust gas after-treatment system, the hydrogen fuel engine exhaust gas after-treatment system comprising:

[0006] An exhaust gas pipeline includes an intake main pipeline, a first parallel pipeline, a second parallel pipeline, and an outlet main pipeline, wherein the air inlet of the intake main pipeline is connected to the air outlet of the hydrogen fuel engine, the air outlet of the intake main pipeline is connected to the air inlets of the first parallel pipeline and the second parallel pipeline, and the air inlet of the outlet main pipeline is connected to the air outlet of the first parallel pipeline and the second parallel pipeline;

[0007] A temperature sensor is provided in the main air intake line;

[0008] A three-way valve, wherein the air inlet of the three-way valve is connected to the air outlet of the main air inlet pipeline, the first air outlet of the three-way valve is connected to the air inlet of the first parallel pipeline, and the second air outlet of the three-way valve is connected to the air inlet of the second parallel pipeline;

[0009] a hydrogen-oxygen catalyst, disposed in the first parallel pipeline;

[0010] an ammonia selective catalytic reduction device, disposed in the first parallel pipeline, downstream of the hydrogen-oxygen catalyst; and

[0011] The hydrogen selective catalytic reduction device is arranged in the second parallel pipeline.

[0012] Furthermore, in one embodiment, the first hydrogen injector is configured to inject hydrogen into the cylinder after the power stroke ends, and the first hydrogen injector is a hydrogen injector of a hydrogen fuel engine.

[0013] Furthermore, in one embodiment, the hydrogen fuel engine exhaust after-treatment system further includes:

[0014] The second hydrogen injector is arranged in the second parallel pipeline and is located upstream of the hydrogen selective catalytic reduction device.

[0015] Furthermore, in one embodiment, the hydrogen fuel engine exhaust after-treatment system further includes:

[0016] The nitrogen oxide sensor is installed in the downstream pipeline of the hydrogen selective catalytic reduction device.

[0017] Furthermore, in one embodiment, the hydrogen fuel engine exhaust after-treatment system further includes:

[0018] The hydrogen sensor is arranged in the downstream pipeline of the hydrogen selective catalytic reduction device.

[0019] In a second aspect, an embodiment of the present application provides a method for after-treatment of exhaust gas from a hydrogen fuel engine, which is applied to the above-mentioned hydrogen fuel engine exhaust gas after-treatment system. The method for after-treatment of exhaust gas from a hydrogen fuel engine comprises:

[0020] When the measured value of the temperature sensor is greater than a first temperature threshold, the first air outlet of the three-way valve is opened, the second air outlet of the three-way valve is closed, and the hydrogen-oxygen catalyst and the ammonia selective catalytic reduction device are turned on;

[0021] When the measured value of the temperature sensor is less than or equal to the second temperature threshold, the second gas outlet of the three-way valve is opened, the second gas outlet of the three-way valve is closed, and the hydrogen selective catalytic reduction device is started, wherein the second temperature threshold is less than or equal to the first temperature threshold.

[0022] Furthermore, in one embodiment, the hydrogen fuel engine exhaust post-processing method further includes:

[0023] When the measured value of the temperature sensor is less than or equal to a second temperature threshold and the measured value of the nitrogen oxide sensor is greater than a first concentration threshold, the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke is increased, wherein the first hydrogen injector is a hydrogen injector of a hydrogen fuel engine, and the nitrogen oxide sensor is arranged in a downstream pipeline of the hydrogen selective catalytic reduction device.

[0024] Furthermore, in one embodiment, the hydrogen fuel engine exhaust post-processing method further includes:

[0025] When the measurement value of the temperature sensor is less than or equal to the second temperature threshold and the measurement value of the nitrogen oxide sensor is greater than the first concentration threshold, the amount of hydrogen injected by the second hydrogen injector into the second parallel pipeline is increased, wherein the second hydrogen injector is arranged in the second parallel pipeline, upstream of the hydrogen selective catalytic reduction device, and the nitrogen oxide sensor is arranged in the downstream pipeline of the hydrogen selective catalytic reduction device.

[0026] Furthermore, in one embodiment, the hydrogen fuel engine exhaust post-processing method further includes:

[0027] When a measurement value of the temperature sensor is less than or equal to a second temperature threshold, a measurement value of the hydrogen sensor is greater than a second concentration threshold, and an amount of hydrogen injected into the cylinder by the first hydrogen injector after a power stroke is greater than zero, reducing the amount of hydrogen injected into the cylinder by the first hydrogen injector after a power stroke, wherein the first hydrogen injector is a hydrogen injector of a hydrogen fuel engine, and the hydrogen sensor is disposed in a downstream pipeline of a hydrogen selective catalytic reduction device;

[0028] When the measurement value of the temperature sensor is less than or equal to the second temperature threshold, the measurement value of the hydrogen sensor is greater than the second concentration threshold, and the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke is equal to zero, the amount of hydrogen injected into the cylinder by the first hydrogen injector before the start of the power stroke is reduced.

[0029] Furthermore, in one embodiment, the hydrogen fuel engine exhaust post-processing method further includes:

[0030] When the measured value of the temperature sensor is less than or equal to a second temperature threshold, the measured value of the hydrogen sensor is greater than a second concentration threshold, and the amount of hydrogen injected into the second parallel pipeline by the second hydrogen injector is greater than zero, reducing the amount of hydrogen injected into the second parallel pipeline by the second hydrogen injector, wherein the first hydrogen injector is a hydrogen injector of a hydrogen fuel engine, and the hydrogen sensor is disposed in a downstream pipeline of the hydrogen selective catalytic reduction device;

[0031] When the measurement value of the temperature sensor is less than or equal to the second temperature threshold, the measurement value of the hydrogen sensor is greater than the second concentration threshold, and the amount of hydrogen injected into the second parallel pipeline by the second hydrogen injector is equal to zero, the amount of hydrogen injected into the cylinder by the first hydrogen injector before the start of the power stroke is reduced, wherein the first hydrogen injector is a hydrogen injector of a hydrogen fuel engine.

[0032] In this application, when the exhaust gas enters the first parallel pipeline for post-processing, the hydrogen in the exhaust gas is first removed by the hydrogen-oxygen catalyst, and then the nitrogen oxides in the exhaust gas are removed by the ammonia selective catalytic reduction device, which can ensure high conversion efficiency under medium and high temperature conditions. When the exhaust gas enters the second parallel pipeline for post-processing, the nitrogen oxides and hydrogen in the exhaust gas are removed by the hydrogen selective catalytic reduction device, which can ensure high conversion efficiency under medium and low temperature conditions. The measured value of the temperature sensor can be used as the control basis of the three-way valve. Through this application, a reasonable selection of exhaust gas post-processing method is made based on the original exhaust temperature of the hydrogen fuel engine, thereby effectively suppressing nitrogen oxide and hydrogen emissions under all operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic structural diagram of an exhaust gas after-treatment system for a hydrogen fuel engine in one embodiment of the present application;

[0034] Figure 2 This is a schematic structural diagram of an exhaust gas after-treatment system for a hydrogen fuel engine in another embodiment of the present application;

[0035] Figure 3 Schematic diagram of the process of after-treatment of exhaust gas from a hydrogen fuel engine in one embodiment of the present application

[0036] Figure 4 Schematic diagram of temperature-conversion efficiency curves of an ammonia selective catalytic reduction device and a hydrogen selective catalytic reduction device in one embodiment of the present application.

[0037] Description of reference numerals:

[0038] 1. Exhaust pipe; 11. Intake main line; 12. First parallel line; 13. Second parallel line; 14. Exhaust main line; 2. Temperature sensor; 3. Three-way valve; 4. Hydrogen-oxygen catalyst; 5. Ammonia selective catalytic reduction device; 51. Urea injector; 52. Catalyst; 53. Ammonia slip catalyst; 6. Hydrogen selective catalytic reduction device; 7. Nitrogen oxide sensor; 8. Hydrogen sensor. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0040] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0041] In a first aspect, an embodiment of the present application provides an exhaust after-treatment system for a hydrogen fuel engine.

[0042] Figure 1 A schematic structural diagram of an exhaust gas after-treatment system for a hydrogen fuel engine in one embodiment of the present application is shown.

[0043] Reference Figure 1 In one embodiment, the exhaust after-treatment system of a hydrogen fuel engine includes an exhaust pipeline 1, a temperature sensor 2, a three-way valve 3, a hydrogen-oxygen catalyst 4, an ammonia selective catalytic reduction device 5 and a hydrogen selective catalytic reduction device 6.

[0044] The exhaust gas pipeline 1 includes an intake main pipeline 11, a first parallel pipeline 12, a second parallel pipeline 13 and an outlet main pipeline 14. The air inlet of the intake main pipeline 11 is connected to the air outlet of the hydrogen fuel engine (not shown in the figure), the air outlet of the intake main pipeline 11 is connected to the air inlets of the first parallel pipeline 12 and the second parallel pipeline 13, and the air inlet of the outlet main pipeline 14 is connected to the air outlet of the first parallel pipeline 12 and the second parallel pipeline 13.

[0045] The temperature sensor 2 is provided on the main air intake line 11. The air inlet of the three-way valve 3 is connected to the air outlet of the main air intake line 11, the first air outlet of the three-way valve 3 is connected to the air inlet of the first parallel line 12, and the second air outlet of the three-way valve 3 is connected to the air inlet of the second parallel line 13.

[0046] The hydrogen-oxygen catalyst 4 is disposed in the first parallel pipeline 12 , and the ammonia selective catalytic reduction device 5 is disposed in the first parallel pipeline 12 , downstream of the hydrogen-oxygen catalyst 4 . The hydrogen selective catalytic reduction device 6 is disposed in the second parallel pipeline 13 .

[0047] Specifically, the ammonia selective catalytic reduction device 5 includes a urea injector 51, a catalyst 52, and an ammonia slip catalyst 53. The urea injector 51 is used to inject urea aqueous solution into the exhaust gas, hydrolyzing it to produce ammonia. The catalyst 52 provides a reaction environment and the necessary catalytic action for the selective catalytic reduction reaction of ammonia and nitrogen oxides. The ammonia slip catalyst 53 removes excess ammonia that does not participate in the reaction.

[0048] The raw exhaust temperature refers to the temperature of the exhaust gas produced by the combustion of fuel in the engine combustion chamber when it is first discharged into the exhaust system. The hydrogen-oxygen catalyst (HOC) mainly uses a specific catalyst to promote the oxidation reaction between hydrogen and oxygen to produce water, thereby achieving the purpose of reducing hydrogen emissions. The ammonia selective catalytic reduction device (NH3-SCR) uses ammonia as a reducing agent. Under the action of the catalyst, it selectively reacts chemically with nitrogen oxides in the exhaust gas, reducing them to nitrogen and water, thereby achieving the purpose of reducing nitrogen oxide emissions. The ammonia selective catalytic reduction device has a high conversion efficiency for nitrogen oxides under medium and high temperature operating conditions. Under low temperature conditions (for example, the raw exhaust temperature is between 0-150°C), the conversion efficiency for nitrogen oxides is low. The hydrogen-oxygen catalyst cannot ignite under low temperature conditions.

[0049] The purpose of placing the hydrogen-oxygen catalyst upstream of the ammonia selective catalytic reduction unit is to utilize the heat released by the hydrogen-oxygen catalyst reaction to raise the exhaust gas temperature upon entering the ammonia selective catalytic reduction unit, thereby improving the nitrogen oxide conversion efficiency. By controlling the first outlet of three-way valve 3 to open and the second outlet to close, the exhaust gas can be post-processed in the first parallel pipeline 12. The raw exhaust temperature can be collected by temperature sensor 2 and used as a control basis for the three-way valve, thus eliminating low-temperature operating conditions and ensuring the conversion efficiency of the exhaust gas during post-processing in the first parallel pipeline 12.

[0050] Specifically, the hydrogen selective catalytic reduction device (H2-SCR) uses hydrogen as a reducing agent. Under the action of a catalyst, it selectively reacts chemically with nitrogen oxides in the exhaust gas, reducing them to nitrogen and water, thereby achieving the purpose of reducing nitrogen oxide emissions. Since the above reaction also requires the consumption of hydrogen, the purpose of reducing hydrogen emissions can also be achieved by rationally controlling the amount of hydrogen. The hydrogen selective catalytic reduction device has a high conversion efficiency for nitrogen oxides under medium and low temperature conditions. Under high temperature conditions (for example, the original exhaust temperature is between 200-300°C), the reaction activity under oxygen-rich conditions is relatively low. The competitive reaction between hydrogen and oxygen inhibits the effect of selective catalytic reduction of nitrogen oxides, resulting in a low conversion efficiency.

[0051] By controlling the second air outlet of the three-way valve 3 to open and the first air outlet to close, the exhaust gas can be allowed to participate in post-processing in the second parallel pipeline 13. The original exhaust temperature can be collected by the temperature sensor 2 as the control basis of the three-way valve, thereby eliminating high-temperature working conditions and ensuring the conversion efficiency of the exhaust gas when participating in post-processing in the second parallel pipeline 13.

[0052] Therefore, in this embodiment, when the exhaust gas enters the first parallel pipeline 12 for post-treatment, hydrogen is first removed from the exhaust gas by the hydrogen-oxygen catalyst 4, and then nitrogen oxides are removed from the exhaust gas by the ammonia selective catalytic reduction device 5. This ensures high conversion efficiency under medium and high temperature operating conditions. When the exhaust gas enters the second parallel pipeline 13 for post-treatment, nitrogen oxides and hydrogen are removed from the exhaust gas by the hydrogen selective catalytic reduction device 6. This ensures high conversion efficiency under medium and low temperature operating conditions. The measured value of the temperature sensor 2 can serve as the control basis for the three-way valve 3. Through this embodiment, the exhaust gas post-treatment method is reasonably selected based on the raw exhaust temperature of the hydrogen fuel engine, thereby effectively suppressing nitrogen oxide and hydrogen emissions under all operating conditions.

[0053] Furthermore, in one embodiment, a first hydrogen injector (not shown) is configured to inject hydrogen into the cylinder after the power stroke ends, and the first hydrogen injector is a hydrogen injector of a hydrogen fuel engine.

[0054] In this embodiment, the hydrogen injected into the cylinder by the hydrogen injector of the hydrogen fuel engine after the power stroke does not participate in combustion, but will all be used as part of the exhaust gas for post-processing to achieve precise regulation of the hydrogen concentration. In this way, there is no need to set up a separate hydrogen injector for the hydrogen selective catalytic reduction device 6, which helps to simplify the structure and reduce costs.

[0055] Furthermore, in one embodiment, the hydrogen fuel engine exhaust after-treatment system further includes a second hydrogen injector (not shown), which is disposed in the second parallel pipeline and located upstream of the hydrogen selective catalytic reduction device 6 .

[0056] In this embodiment, a hydrogen injector is separately provided for the hydrogen selective catalytic reduction device 6 in the second parallel pipeline to achieve precise regulation of the hydrogen concentration.

[0057] Furthermore, in one embodiment, the exhaust after-treatment system of the hydrogen fuel engine further includes a nitrogen oxide sensor, which is disposed in a downstream pipeline of the hydrogen selective catalytic reduction device 6 .

[0058] In this embodiment, a nitrogen oxide sensor is provided in the downstream pipeline of the hydrogen selective catalytic reduction device 6 to monitor the nitrogen oxide concentration of the exhaust gas after entering the second parallel pipeline 13 for post-treatment, thereby performing feedback adjustment on the hydrogen injection amount of the first hydrogen injector or the second hydrogen injector.

[0059] Specifically, it is provided in the downstream pipeline of the hydrogen selective catalytic reduction device 6 , that is, provided in the second parallel pipeline 13 and located downstream of the hydrogen selective catalytic reduction device 6 , or provided in the main gas outlet pipeline 14 .

[0060] Figure 2 A schematic structural diagram of an exhaust gas after-treatment system for a hydrogen fuel engine in another embodiment of the present application is shown.

[0061] Reference Figure 2 The nitrogen oxide sensor 7 is arranged in the main exhaust pipe 14. In this way, the nitrogen oxide sensor 7 can also monitor the nitrogen oxide concentration of the exhaust gas after entering the first parallel pipe 12 for post-processing, thereby feedback-adjusting the urea injection amount of the urea injector 51.

[0062] Furthermore, in one embodiment, the hydrogen fuel engine exhaust gas after-treatment system further includes a hydrogen sensor, which is disposed in a downstream pipeline of the hydrogen selective catalytic reduction device 6 .

[0063] In this embodiment, a hydrogen sensor is provided in the downstream pipeline of the hydrogen selective catalytic reduction device 6 to monitor the hydrogen concentration of the exhaust gas after entering the second parallel pipeline 13 for post-processing, thereby performing feedback adjustment on the hydrogen injection amount of the first hydrogen injector or the second hydrogen injector.

[0064] Continue to refer to Figure 2 The hydrogen sensor 8 is arranged in the main outlet pipe 14. In this way, the hydrogen sensor 8 can also monitor the hydrogen concentration of the exhaust gas after entering the first parallel pipe 12 for post-processing, thereby providing more effective information for post-processing control, for example, for feedback adjustment of the urea injection amount of the urea injector 51.

[0065] In a second aspect, an embodiment of the present application further provides a method for after-treatment of exhaust gas from a hydrogen fuel engine, which is applied to the above-mentioned exhaust gas after-treatment system of a hydrogen fuel engine.

[0066] Figure 3 A schematic flow chart of a method for after-treatment of exhaust gas from a hydrogen fuel engine in one embodiment of the present application is shown.

[0067] Reference Figure 1 and Figure 3 , hydrogen fuel engine exhaust after-treatment methods include:

[0068] S1. When the measured value of the temperature sensor 2 is greater than the first temperature threshold, the first air outlet of the three-way valve 3 is opened, the second air outlet of the three-way valve 3 is closed, and the hydrogen-oxygen catalyst 4 and the ammonia selective catalytic reduction device 5 are turned on;

[0069] S2. When the measurement value of the temperature sensor 2 is less than or equal to the second temperature threshold, the second gas outlet of the three-way valve 3 is opened, the second gas outlet of the three-way valve 3 is closed, and the hydrogen selective catalytic reduction device 6 is turned on, wherein the second temperature threshold is less than or equal to the first temperature threshold.

[0070] It can be understood that the first temperature threshold is used to exclude low temperature conditions to ensure the conversion efficiency of the exhaust gas when it participates in post-processing in the first parallel pipeline 12, and the second temperature threshold is used to exclude high temperature conditions to ensure the conversion efficiency of the exhaust gas when it participates in post-processing in the second parallel pipeline 13.

[0071] It should be noted that when the second temperature threshold is set equal to the first temperature threshold, the measured value of temperature sensor 2 (i.e., the original exhaust temperature of the hydrogen fuel engine) is the sole basis for selecting the exhaust after-treatment method. Considering that there is a certain temperature range where the conversion efficiency of the two exhaust after-treatment methods is not significantly different and is within an acceptable range, the second temperature threshold can also be set lower than the first temperature threshold. When the measured value of temperature sensor 2 is less than or equal to the first temperature threshold and greater than the second temperature threshold, either exhaust after-treatment method can be used, or other criteria can be introduced for selection.

[0072] Furthermore, in one embodiment, the hydrogen fuel engine exhaust post-processing method further includes:

[0073] When the measurement value of the temperature sensor 2 is less than or equal to the second temperature threshold, and the measurement value of the nitrogen oxide sensor is greater than the first concentration threshold, the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke is increased, wherein the first hydrogen injector is a hydrogen injector of a hydrogen fuel engine, and the nitrogen oxide sensor is arranged in the downstream pipeline of the hydrogen selective catalytic reduction device 6.

[0074] In this embodiment, the high measurement value of the nitrogen oxide sensor indicates that there is insufficient hydrogen in the second parallel pipeline 13 for post-processing. It is necessary to increase the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke until the measurement value of the nitrogen oxide sensor drops to an acceptable range.

[0075] The relevant descriptions of the first hydrogen injector and the nitrogen oxide sensor refer to the previous embodiments and will not be repeated here.

[0076] Furthermore, in one embodiment, the hydrogen fuel engine exhaust post-processing method further includes:

[0077] When the measurement value of the temperature sensor 2 is less than or equal to the second temperature threshold, and the measurement value of the nitrogen oxide sensor is greater than the first concentration threshold, the amount of hydrogen injected by the second hydrogen injector into the second parallel pipeline 13 is increased, wherein the second hydrogen injector is arranged in the second parallel pipeline 13, upstream of the hydrogen selective catalytic reduction device 6, and the nitrogen oxide sensor is arranged in the downstream pipeline of the hydrogen selective catalytic reduction device 6.

[0078] In this embodiment, if the measurement value of the nitrogen oxide sensor is too high, it means that there is insufficient hydrogen in the second parallel pipeline 13 for post-processing. It is necessary to increase the amount of hydrogen injected into the second parallel pipeline 13 by the second hydrogen injector until the measurement value of the nitrogen oxide sensor drops to an acceptable range.

[0079] The relevant descriptions of the second hydrogen injector and the nitrogen oxide sensor refer to the previous embodiments and will not be repeated here.

[0080] Furthermore, in one embodiment, the hydrogen fuel engine exhaust post-processing method further includes:

[0081] When the measurement value of the temperature sensor 2 is less than or equal to the second temperature threshold, the measurement value of the hydrogen sensor is greater than the second concentration threshold, and the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke is greater than zero, the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke is reduced, wherein the first hydrogen injector is a hydrogen injector of a hydrogen fuel engine, and the hydrogen sensor is disposed in a downstream pipeline of the hydrogen selective catalytic reduction device 6;

[0082] When the measurement value of the temperature sensor 2 is less than or equal to the second temperature threshold, the measurement value of the hydrogen sensor is greater than the second concentration threshold, and the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke is equal to zero, the amount of hydrogen injected into the cylinder by the first hydrogen injector before the start of the power stroke is reduced.

[0083] In this embodiment, an excessively high measurement value from the hydrogen sensor indicates an excess of hydrogen in the second parallel pipeline 13 for post-processing. Therefore, the hydrogen concentration in the exhaust gas prior to post-processing needs to be reduced until it falls within an acceptable range. Prior to post-processing, the hydrogen in the exhaust gas comes from two sources: a portion of hydrogen injected into the cylinder by the first hydrogen injector before the start of the power stroke, i.e., the remaining hydrogen from the combustion reaction; and all of the hydrogen injected into the cylinder by the first hydrogen injector after the power stroke. Because each combustion reaction is influenced by numerous factors, the amount of remaining hydrogen is difficult to precisely control. Therefore, when reducing the hydrogen concentration in the exhaust gas prior to post-processing, the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke is prioritized. After reducing it to zero, the amount of hydrogen injected into the cylinder by the first hydrogen injector before the start of the power stroke is then reduced.

[0084] The relevant descriptions of the first hydrogen injector and the hydrogen sensor refer to the above embodiments and will not be repeated here.

[0085] Furthermore, in one embodiment, the hydrogen fuel engine exhaust post-processing method further includes:

[0086] When the measurement value of the temperature sensor 2 is less than or equal to the second temperature threshold, the measurement value of the hydrogen sensor is greater than the second concentration threshold, and the amount of hydrogen injected into the second parallel pipeline 13 by the second hydrogen injector is greater than zero, the amount of hydrogen injected into the second parallel pipeline 13 by the second hydrogen injector is reduced, wherein the first hydrogen injector is a hydrogen injector of a hydrogen fuel engine, and the hydrogen sensor is provided in a downstream pipeline of the hydrogen selective catalytic reduction device 6;

[0087] When the measurement value of the temperature sensor 2 is less than or equal to the second temperature threshold, the measurement value of the hydrogen sensor is greater than the second concentration threshold, and the amount of hydrogen injected into the second parallel pipe 13 by the second hydrogen injector is equal to zero, the amount of hydrogen injected into the cylinder by the first hydrogen injector before the start of the power stroke is reduced, wherein the first hydrogen injector is the hydrogen injector of the hydrogen fuel engine.

[0088] In this embodiment, an excessively high measurement value from the hydrogen sensor indicates an excess of hydrogen in the second parallel line 13 for post-processing. Therefore, the hydrogen concentration in the exhaust gas prior to post-processing needs to be reduced until it falls within an acceptable range. Prior to post-processing, the hydrogen in the exhaust gas comes from two sources: a portion of hydrogen injected into the cylinder by the first hydrogen injector before the start of the power stroke, i.e., the remaining hydrogen from the combustion reaction; and all of the hydrogen injected into the second parallel line 13 by the second hydrogen injector. Because each combustion reaction is influenced by numerous factors, the amount of remaining hydrogen is difficult to precisely control. Therefore, when reducing the hydrogen concentration in the exhaust gas prior to post-processing, the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke is prioritized. After this amount is reduced to zero, the amount of hydrogen injected into the second parallel line 13 by the second hydrogen injector is then reduced.

[0089] The relevant descriptions of the first hydrogen injector, the second hydrogen injector and the hydrogen sensor refer to the previous embodiments and will not be repeated here.

[0090] It will be appreciated that the above embodiment describes how to reasonably control the amount of hydrogen involved in the post-processing of the exhaust gas entering the second parallel pipeline 13. In practice, the amount of ammonia involved in the post-processing of the exhaust gas entering the first parallel pipeline 12 also needs to be reasonably controlled. Since ammonia selective catalytic reduction technology is highly mature, reference can be made to relevant literature and no further details will be given here.

[0091] Furthermore, in one embodiment, the first temperature threshold is the original exhaust temperature when the hydrogen fuel engine is operating at the target operating point;

[0092] Among the different test operating points, the emission quantification value corresponding to the target operating point is the lowest;

[0093] The emission quantification value is a weighted calculation result of the nitrogen oxide concentration and hydrogen concentration in the exhaust gas after post-processing in the first parallel pipeline 12 when the hydrogen fuel engine is operating at the corresponding test operating point;

[0094] The test operating point is a common operating point of the hydrogen fuel engine. When the hydrogen fuel engine is operating at the test operating point, the absolute value of the difference between the original exhaust temperature of the hydrogen fuel engine and the reference temperature is less than or equal to the preset span;

[0095] When the exhaust temperature of the hydrogen fuel engine is equal to the reference temperature, the theoretical conversion efficiencies of the ammonia selective catalytic reduction device and the hydrogen selective catalytic reduction device for nitrogen oxides are equal.

[0096] In this embodiment, the second temperature threshold is set equal to the first temperature threshold, and a method for determining the first temperature threshold is provided. In this embodiment, when the measurement value of temperature sensor 2 is used as the sole basis for selecting the exhaust after-treatment method, the temperature threshold serving as the switching point can be reasonably determined, thereby improving the suppression effect of nitrogen oxide and hydrogen emissions under all operating conditions.

[0097] Figure 4 A schematic diagram showing temperature-conversion efficiency curves of an ammonia selective catalytic reduction device and a hydrogen selective catalytic reduction device in one embodiment of the present application is shown.

[0098] For example, refer to Figure 4 First, find the intersection of the temperature-conversion efficiency curves of the ammonia selective catalytic reduction device and the hydrogen selective catalytic reduction device. Figure 2 The temperature T0 corresponding to the intersection in is the reference temperature. Then, among the commonly used operating points of the hydrogen fuel engine, find the operating point where the original exhaust temperature is close to the reference temperature (for example, T0±20°C) as the test operating point. Next, when the hydrogen fuel engine is working at different test operating points, the nitrogen oxide concentration and hydrogen concentration in the exhaust gas after post-treatment in the first parallel pipeline 12 are obtained, and a weighted calculation is performed to obtain the emission quantification value. The weight is set as needed. For example, nitrogen oxides are pollutants defined by relevant regulations, and their weights can be set relatively higher. The lower the emission quantification value, the better the effect of the exhaust gas post-treatment. Finally, the test operating point with the lowest emission quantification value is determined as the target operating point, and the original exhaust temperature of the hydrogen fuel engine when the hydrogen fuel engine is working at the target operating point is determined as the first temperature threshold.

[0099] Furthermore, in one embodiment, the second temperature threshold is less than the first temperature threshold;

[0100] The hydrogen fuel engine exhaust post-processing method further comprises:

[0101] When the measurement value of the temperature sensor 2 is less than or equal to the first temperature threshold and greater than the second temperature threshold, and the measurement value of the hydrogen sensor is less than or equal to the third concentration threshold, the first gas outlet of the three-way valve 3 is opened, the second gas outlet of the three-way valve 3 is closed, and the hydrogen-oxygen catalyst 4 and the ammonia selective catalytic reduction device 5 are turned on, wherein the hydrogen sensor is arranged in the downstream pipeline of the ammonia selective catalytic reduction device 5;

[0102] When the measurement value of the temperature sensor 2 is less than or equal to the first temperature threshold and greater than the second temperature threshold, and the measurement value of the hydrogen sensor is greater than the third concentration threshold, the second gas outlet of the three-way valve 3 is opened, the second gas outlet of the three-way valve 3 is closed, and the hydrogen selective catalytic reduction device 6 is started.

[0103] In this embodiment, the second temperature threshold is set to be lower than the first temperature threshold. When the measurement value of temperature sensor 2 is less than or equal to the first temperature threshold but greater than the second temperature threshold, the measurement value of the hydrogen sensor is introduced as an additional reference. When the measurement value of the hydrogen sensor is high, it is determined that the first parallel pipeline 12 is unable to effectively control hydrogen emissions and that the second parallel pipeline 13 is required for exhaust gas post-treatment. Through this embodiment, the exhaust gas post-treatment method can be reasonably selected in the intermediate temperature range based on the hydrogen removal situation during actual operation, thereby improving the suppression effect of nitrogen oxides and hydrogen under all operating conditions.

[0104] Specifically, it is provided in the downstream pipeline of the ammonia selective catalytic reduction device 5 , that is, provided in the first parallel pipeline 12 and located downstream of the ammonia selective catalytic reduction device 5 , or provided in the main gas outlet pipeline 14 .

[0105] Continue to refer to Figure 2 The hydrogen sensor 8 is arranged in the main outlet pipe 14. In this way, the hydrogen sensor 8 can also monitor the hydrogen concentration of the exhaust gas after entering the second parallel pipe 13 for post-processing, thereby providing more effective information for post-processing control, for example, for feedback adjustment of the hydrogen injection amount of the first hydrogen injector or the second hydrogen injector.

[0106] It should be noted that the serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0107] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application 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 this application. 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 an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0108] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit the "first", "second" and "third" to different types.

[0109] In the description of the embodiments of this application, the words "exemplary," "for example," or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary," "for example," or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary," "for example," or "for example" is intended to present the relevant concepts in a concrete manner.

[0110] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; “and / or” in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, “multiple” refers to two or more than two.

[0111] In some processes described in the embodiments of the present application, multiple operations or steps are included that appear in a specific order. However, it should be understood that these operations or steps may not be performed in the order in which they appear in the embodiments of the present application or may be performed in parallel. The sequence numbers of the operations are only used to distinguish between different operations, and the sequence numbers themselves do not represent any order of execution. In addition, these processes may include more or fewer operations, and these operations or steps may be performed in sequence or in parallel, and these operations or steps may be combined.

[0112] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, of course, it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes a number of instructions for enabling a terminal device to execute the methods described in each embodiment of the present application.

[0113] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A hydrogen fuel engine exhaust after-treatment system, characterized in that: The first hydrogen injector is configured to inject hydrogen into the cylinder after the power stroke. The first hydrogen injector is a hydrogen injector of a hydrogen fuel engine. The exhaust after-treatment system of the hydrogen fuel engine includes: An exhaust gas pipeline includes an intake main pipeline, a first parallel pipeline, a second parallel pipeline, and an outlet main pipeline, wherein the air inlet of the intake main pipeline is connected to the air outlet of the hydrogen fuel engine, the air outlet of the intake main pipeline is connected to the air inlets of the first parallel pipeline and the second parallel pipeline, and the air inlet of the outlet main pipeline is connected to the air outlet of the first parallel pipeline and the second parallel pipeline; A temperature sensor is provided in the main air intake line; A three-way valve, wherein the air inlet of the three-way valve is connected to the air outlet of the main air inlet pipeline, the first air outlet of the three-way valve is connected to the air inlet of the first parallel pipeline, and the second air outlet of the three-way valve is connected to the air inlet of the second parallel pipeline; a hydrogen-oxygen catalyst, disposed in the first parallel pipeline; an ammonia selective catalytic reduction device, disposed in the first parallel pipeline, downstream of the hydrogen-oxygen catalyst; and a hydrogen selective catalytic reduction device, disposed in the second parallel pipeline; The second hydrogen injector is arranged in the second parallel pipeline and is located upstream of the hydrogen selective catalytic reduction device.

2. The hydrogen fuel engine exhaust after-treatment system according to claim 1, characterized in that: The hydrogen fuel engine exhaust after-treatment system further includes: The nitrogen oxide sensor is installed in the downstream pipeline of the hydrogen selective catalytic reduction device.

3. The hydrogen fuel engine exhaust after-treatment system according to claim 1, characterized in that: The hydrogen fuel engine exhaust after-treatment system further includes: The hydrogen sensor is arranged in the downstream pipeline of the hydrogen selective catalytic reduction device.

4. A method for post-processing exhaust gas from a hydrogen fuel engine, characterized in that: The hydrogen fuel engine exhaust gas after-treatment system according to any one of claims 1 to 3 is applied, and the hydrogen fuel engine exhaust gas after-treatment method comprises: When the measured value of the temperature sensor is greater than a first temperature threshold, the first air outlet of the three-way valve is opened, the second air outlet of the three-way valve is closed, and the hydrogen-oxygen catalyst and the ammonia selective catalytic reduction device are turned on; When the measured value of the temperature sensor is less than or equal to a second temperature threshold, the second gas outlet of the three-way valve is opened, the first gas outlet of the three-way valve is closed, and the hydrogen selective catalytic reduction device is started, wherein the second temperature threshold is less than or equal to the first temperature threshold.

5. The method for post-processing exhaust gas from a hydrogen fuel engine according to claim 4, wherein: The hydrogen fuel engine exhaust post-processing method further comprises: When the measured value of the temperature sensor is less than or equal to a second temperature threshold and the measured value of the nitrogen oxide sensor is greater than a first concentration threshold, the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke is increased, wherein the nitrogen oxide sensor is arranged in a downstream pipeline of the hydrogen selective catalytic reduction device.

6. The method for post-processing exhaust gas from a hydrogen fuel engine according to claim 4, wherein: The hydrogen fuel engine exhaust post-processing method further comprises: When the measured value of the temperature sensor is less than or equal to the second temperature threshold and the measured value of the nitrogen oxide sensor is greater than the first concentration threshold, the amount of hydrogen injected by the second hydrogen injector into the second parallel pipeline is increased, wherein the nitrogen oxide sensor is arranged in the downstream pipeline of the hydrogen selective catalytic reduction device.

7. The method for post-processing exhaust gas from a hydrogen fuel engine according to claim 4, wherein: The hydrogen fuel engine exhaust post-processing method further comprises: When the measured value of the temperature sensor is less than or equal to a second temperature threshold, the measured value of the hydrogen sensor is greater than a second concentration threshold, and the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke is greater than zero, reducing the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke, wherein the hydrogen sensor is disposed in a downstream pipeline of the hydrogen selective catalytic reduction device; When the measurement value of the temperature sensor is less than or equal to the second temperature threshold, the measurement value of the hydrogen sensor is greater than the second concentration threshold, and the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke is equal to zero, the amount of hydrogen injected into the cylinder by the first hydrogen injector before the start of the power stroke is reduced.

8. The method for post-processing exhaust gas from a hydrogen fuel engine according to claim 4, wherein: The hydrogen fuel engine exhaust post-processing method further comprises: When the measurement value of the temperature sensor is less than or equal to the second temperature threshold, the measurement value of the hydrogen sensor is greater than the second concentration threshold, and the amount of hydrogen injected into the second parallel pipeline by the second hydrogen injector is greater than zero, reducing the amount of hydrogen injected into the second parallel pipeline by the second hydrogen injector, wherein the hydrogen sensor is disposed in a downstream pipeline of the hydrogen selective catalytic reduction device; When the measured value of the temperature sensor is less than or equal to the second temperature threshold, the measured value of the hydrogen sensor is greater than the second concentration threshold, and the amount of hydrogen injected into the second parallel pipeline by the second hydrogen injector is equal to zero, the amount of hydrogen injected into the cylinder by the first hydrogen injector before the start of the power stroke is reduced.

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