Hydrogen fuel engine tail gas after-treatment method and device

Abstract

The invention provides a hydrogen fuel engine tail gas aftertreatment method and device.The method comprises the steps that when the original exhaust temperature of a hydrogen fuel engine is larger than a first temperature threshold value, tail gas is controlled to enter a first pipeline to participate in aftertreatment, and the first pipeline is provided with a hydrogen-oxygen catalyst and an ammonia selective catalytic reduction device; the hydrogen-oxygen catalyst is located at the upstream of the ammonia selective catalytic reduction device; and when the original exhaust temperature of the hydrogen fuel engine is smaller than or equal to a second temperature threshold value, the tail gas is controlled to enter a second pipeline to participate in aftertreatment, the second temperature threshold value is smaller than or equal to the first temperature threshold value, and the second pipeline is provided with a hydrogen selective catalytic reduction device. According to the tail gas aftertreatment method and device, the tail gas aftertreatment mode is reasonably selected on the basis of the original exhaust temperature of the hydrogen fuel engine, and therefore emission of nitrogen oxide and hydrogen under the full working condition is effectively restrained.

Description

Technical Field

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

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

[0003] There are two main technical routes for engine exhaust aftertreatment at present: one is the NH3-SCR route, which uses an ammonia selective catalytic reduction device to remove nitrogen oxides from exhaust gas; the other is the H2-SCR route, which uses a hydrogen selective catalytic reduction device to remove nitrogen oxides from exhaust gas. However, when these two technical routes are applied to hydrogen fuel engines, they cannot effectively suppress nitrogen oxide and hydrogen emissions under all working conditions. Summary of the invention

[0004] The present application provides a method and device for after-treatment of exhaust gas from a hydrogen fuel engine, which can solve the technical problem in the prior art that it is impossible 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 method for post-processing exhaust gas from a hydrogen fuel engine, the method comprising:

[0006] When the original exhaust temperature of the hydrogen fuel engine is greater than a first temperature threshold, the exhaust gas is controlled to enter the first pipeline for post-processing, wherein the first pipeline is provided with a hydrogen-oxygen catalyst and an ammonia selective catalytic reduction device, and the hydrogen-oxygen catalyst is located upstream of the ammonia selective catalytic reduction device;

[0007] When the original exhaust temperature of the hydrogen fuel engine is less than or equal to a second temperature threshold, the exhaust gas is controlled to enter the second pipeline for post-processing, wherein the second temperature threshold is less than or equal to the first temperature threshold, and the second pipeline is provided with a hydrogen selective catalytic reduction device.

[0008] Further, in one embodiment, the second temperature threshold is equal to the first temperature threshold;

[0009] The first temperature threshold is the original exhaust temperature when the hydrogen fuel engine is operating at the target operating point;

[0010] Among the different test operating points, the emission quantification value corresponding to the target operating point is the lowest;

[0011] The emission quantification value is the weighted calculation result of the nitrogen oxide concentration and hydrogen concentration in the exhaust gas entering the first pipeline after post-treatment when the hydrogen fuel engine is working at the corresponding test operating point;

[0012] 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 and the reference temperature of the hydrogen fuel engine is less than or equal to the preset span;

[0013] 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.

[0014] Further, in one embodiment, the second temperature threshold is less than the first temperature threshold;

[0015] The hydrogen fuel engine exhaust post-treatment method further comprises:

[0016] When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the first temperature threshold and greater than the second temperature threshold, and the hydrogen concentration in the exhaust gas after post-treatment is less than or equal to the first concentration threshold, the exhaust gas is controlled to enter the first pipeline for post-treatment;

[0017] When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the first temperature threshold and greater than the second temperature threshold, and the hydrogen concentration in the exhaust gas after post-processing is greater than the first concentration threshold, the exhaust gas is controlled to enter the second pipeline for post-processing.

[0018] Furthermore, in one embodiment, the hydrogen fuel engine exhaust post-treatment method further comprises:

[0019] When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the second temperature threshold, and the nitrogen oxide concentration in the exhaust gas after post-processing is greater than the second concentration threshold, the hydrogen concentration in the exhaust gas before post-processing is increased.

[0020] Further, in one embodiment, the step of increasing the hydrogen concentration in the tail gas before post-processing comprises:

[0021] The amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke is completed is increased, wherein the first hydrogen injector is a hydrogen injector of a hydrogen fuel engine.

[0022] Further, in one embodiment, the step of increasing the hydrogen concentration in the tail gas before post-processing comprises:

[0023] The amount of hydrogen injected into the second pipeline by the second hydrogen injector is increased, wherein the second pipeline is further provided with a second hydrogen injector, and the second hydrogen injector is located upstream of the hydrogen selective catalytic reduction device.

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

[0025] When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the second temperature threshold, and the hydrogen concentration in the exhaust gas after post-processing is greater than the third concentration threshold, the hydrogen concentration in the exhaust gas before post-processing is lowered.

[0026] Further, in one embodiment, the step of lowering the hydrogen concentration in the tail gas before post-processing comprises:

[0027] When 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 first hydrogen injector is a hydrogen injector of a hydrogen fuel engine;

[0028] When the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke ends is equal to zero, the amount of hydrogen injected into the cylinder by the first hydrogen injector before the power stroke starts is reduced.

[0029] Further, in one embodiment, the step of lowering the hydrogen concentration in the tail gas before post-processing comprises:

[0030] When the amount of hydrogen injected into the second pipeline by the second hydrogen injector is greater than zero, the amount of hydrogen injected into the second pipeline by the second hydrogen injector is reduced, wherein the second pipeline is further provided with a second hydrogen injector, and the second hydrogen injector is located upstream of the hydrogen selective catalytic reduction device;

[0031] When the amount of hydrogen injected into the second 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 a second aspect, an embodiment of the present application further provides a hydrogen fuel engine exhaust gas aftertreatment device, the hydrogen fuel engine exhaust gas aftertreatment device comprising:

[0033] A first flow direction control module, used for controlling the exhaust gas to enter the first pipeline for post-processing when the original exhaust temperature of the hydrogen fuel engine is greater than a first temperature threshold, wherein the first pipeline is provided with a hydrogen-oxygen catalyst and an ammonia selective catalytic reduction device, and the hydrogen-oxygen catalyst is located upstream of the ammonia selective catalytic reduction device;

[0034] The second flow direction control module is used to control the exhaust gas to enter the second pipeline for post-processing when the original exhaust temperature of the hydrogen fuel engine is less than or equal to the second temperature threshold, wherein the second temperature threshold is less than or equal to the first temperature threshold, and the second pipeline is provided with a hydrogen selective catalytic reduction device.

[0035] In this application, when the exhaust gas enters the first pipeline for post-treatment, 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 a high conversion efficiency under medium and high temperature conditions. When the exhaust gas enters the second pipeline for post-treatment, the nitrogen oxides and hydrogen in the exhaust gas are removed by the hydrogen selective catalytic reduction device, which can ensure a high conversion efficiency under medium and low temperature conditions. Through this application, a reasonable choice of exhaust post-treatment method is made based on the original exhaust temperature of the hydrogen fuel engine, thereby effectively suppressing the emission of nitrogen oxides and hydrogen under all working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic flow chart of a method for post-processing exhaust gas from a hydrogen fuel engine in one embodiment of the present application;

[0037] Figure 2 It is a 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;

[0038] Figure 3 This is a schematic diagram of the structure of a hydrogen fuel engine exhaust gas aftertreatment system in one embodiment of the present application;

[0039] Figure 4 This is a schematic diagram of the functional modules of a hydrogen fuel engine exhaust after-treatment device in one embodiment of the present application.

[0040] Description of reference numerals:

[0041] 1. Exhaust pipeline; 11. Intake main pipeline; 12. First parallel pipeline; 13. Second parallel pipeline; 14. Exhaust main pipeline; 2. Temperature sensor; 3. Three-way valve; 4. Hydrogen and 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

[0042] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0043] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0044] In a first aspect, an embodiment of the present application provides a method for after-treatment of exhaust gas from a hydrogen fuel engine.

[0045] Figure 1 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.

[0046] Reference Figure 1 In one embodiment, the method for post-processing exhaust gas from a hydrogen fuel engine comprises the following steps:

[0047] S1. When the original exhaust temperature of the hydrogen fuel engine is greater than a first temperature threshold, the exhaust gas is controlled to enter a first pipeline for post-processing, wherein the first pipeline is provided with a hydrogen-oxygen catalyst and an ammonia selective catalytic reduction device, and the hydrogen-oxygen catalyst is located upstream of the ammonia selective catalytic reduction device.

[0048] Specifically, the original exhaust temperature refers to the temperature of the exhaust gas generated by the combustion of fuel in the engine combustion chamber when it is just discharged into the exhaust system. The hydrogen-oxygen catalyst (HOC) mainly uses a specific catalyst to promote the oxidation reaction of 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 to reduce them to nitrogen and water, thereby achieving the purpose of reducing nitrogen oxide emissions. The ammonia selective catalytic reduction device has a higher conversion efficiency for nitrogen oxides under medium and high temperature conditions, and a lower conversion efficiency for nitrogen oxides under low temperature conditions (for example, the original exhaust temperature is 0-150°C). The hydrogen-oxygen catalyst cannot ignite under low temperature conditions.

[0049] In this embodiment, the purpose of arranging the hydrogen-oxygen catalyst upstream of the ammonia selective catalytic reduction device is to utilize the heat released by the reaction in the hydrogen-oxygen catalyst to increase the temperature of the exhaust gas when it enters the ammonia selective catalytic reduction device, thereby improving the conversion efficiency of nitrogen oxides. The first temperature threshold is used to exclude low temperature conditions to ensure the conversion efficiency of the exhaust gas when it enters the first pipeline for post-processing.

[0050] S2. When the original exhaust temperature of the hydrogen fuel engine is less than or equal to a second temperature threshold, the exhaust gas is controlled to enter the second pipeline for post-processing, wherein the second temperature threshold is less than or equal to the first temperature threshold, and the second pipeline is provided with a hydrogen selective catalytic reduction device.

[0051] Specifically, the hydrogen selective catalytic reduction device (H2-SCR) uses hydrogen as a reducing agent, and under the action of a catalyst, selectively reacts chemically with nitrogen oxides in the exhaust gas to reduce them into nitrogen and water, thereby achieving the purpose of reducing nitrogen oxide emissions. Since the above reaction also consumes hydrogen, the purpose of reducing hydrogen emissions can also be achieved by reasonably 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 200-300°C), the reaction activity under oxygen-rich conditions is relatively low, and the competitive reaction between hydrogen and oxygen inhibits the effect of selective catalytic reduction of nitrogen oxides, resulting in a low conversion efficiency.

[0052] In this embodiment, the second temperature threshold is used to exclude high temperature conditions to ensure the conversion efficiency of the exhaust gas when it enters the second pipeline for post-processing. When the second temperature threshold is set equal to the first temperature threshold, the original exhaust temperature is the only basis for selecting the exhaust gas post-processing method. Considering that there is a certain temperature range, the conversion efficiency of the two exhaust gas post-processing methods is not much different and is within an acceptable range. Therefore, the second temperature threshold can also be set to be less than the first temperature threshold. When the original exhaust temperature is less than or equal to the first temperature threshold and greater than the second temperature threshold, any exhaust gas post-processing method can be used, or other bases can be introduced for selection.

[0053] Therefore, in this embodiment, when the exhaust gas enters the first 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 a high conversion efficiency under medium and high temperature conditions. When the exhaust gas enters the second 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 a high conversion efficiency under medium and low temperature conditions. Through this application, a reasonable choice of exhaust post-processing method is made based on the original exhaust temperature of the hydrogen fuel engine, thereby effectively suppressing the emission of nitrogen oxides and hydrogen under all working conditions.

[0054] Further, in one embodiment, the second temperature threshold is equal to the first temperature threshold;

[0055] The first temperature threshold is the original exhaust temperature when the hydrogen fuel engine is operating at the target operating point;

[0056] Among the different test operating points, the emission quantification value corresponding to the target operating point is the lowest;

[0057] The emission quantification value is the weighted calculation result of the nitrogen oxide concentration and hydrogen concentration in the exhaust gas entering the first pipeline after post-treatment when the hydrogen fuel engine is working at the corresponding test operating point;

[0058] 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 and the reference temperature of the hydrogen fuel engine is less than or equal to the preset span;

[0059] 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.

[0060] 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. Through this embodiment, when the original exhaust temperature is used as the only basis for selecting the exhaust post-treatment method, the temperature threshold as the switching point can be reasonably determined, thereby improving the suppression effect of nitrogen oxides and hydrogen emissions under all working conditions.

[0061] Figure 2 A schematic diagram showing temperature-conversion efficiency curves of an ammonia selective catalytic reduction device and a hydrogen selective catalytic reduction device in an embodiment of the present application is shown.

[0062] For example, refer to Figure 2 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 of is the reference temperature. Then, among the common 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 entering the first pipeline for post-treatment 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 exhaust 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.

[0063] Further, in one embodiment, the second temperature threshold is less than the first temperature threshold;

[0064] The hydrogen fuel engine exhaust post-treatment method further comprises:

[0065] When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the first temperature threshold and greater than the second temperature threshold, and the hydrogen concentration in the exhaust gas after post-treatment is less than or equal to the first concentration threshold, the exhaust gas is controlled to enter the first pipeline for post-treatment;

[0066] When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the first temperature threshold and greater than the second temperature threshold, and the hydrogen concentration in the exhaust gas after post-processing is greater than the first concentration threshold, the exhaust gas is controlled to enter the second pipeline for post-processing.

[0067] In this embodiment, the second temperature threshold is set to be less than the first temperature threshold. When the original exhaust temperature is less than or equal to the first temperature threshold and greater than the second temperature threshold, the hydrogen concentration in the exhaust gas after post-treatment is introduced as an additional reference basis. When the hydrogen concentration is high, it is considered that the first pipeline cannot effectively control hydrogen emissions, and the second pipeline needs to be used for exhaust post-treatment. Through this embodiment, the exhaust post-treatment method can be reasonably selected in the intermediate temperature section in combination with the hydrogen removal situation during actual operation, thereby improving the suppression effect of nitrogen oxides and hydrogen under all working conditions.

[0068] Furthermore, in one embodiment, the hydrogen fuel engine exhaust post-treatment method further comprises:

[0069] When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the second temperature threshold, and the nitrogen oxide concentration in the exhaust gas after post-processing is greater than the second concentration threshold, the hydrogen concentration in the exhaust gas before post-processing is increased.

[0070] In this embodiment, the nitrogen oxide concentration of the exhaust gas after entering the second pipeline for post-treatment is monitored. A too high nitrogen oxide concentration indicates insufficient hydrogen for post-treatment, and the hydrogen concentration in the exhaust gas before post-treatment needs to be increased until the nitrogen oxide concentration is reduced to an acceptable range.

[0071] As an optional implementation, the step of increasing the hydrogen concentration in the tail gas before post-treatment includes:

[0072] The amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke is completed is increased, wherein the first hydrogen injector is a hydrogen injector of a hydrogen fuel engine.

[0073] 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 participate in post-processing as part of the exhaust gas, thereby achieving precise adjustment of the hydrogen concentration. In this way, there is no need to separately set up a hydrogen injector for the hydrogen selective catalytic reduction device, which helps to simplify the structure and reduce costs.

[0074] As another optional implementation, the step of increasing the hydrogen concentration in the tail gas before post-treatment includes:

[0075] The amount of hydrogen injected into the second pipeline by the second hydrogen injector is increased, wherein the second pipeline is further provided with a second hydrogen injector, and the second hydrogen injector is located upstream of the hydrogen selective catalytic reduction device.

[0076] In this embodiment, a hydrogen injector is separately provided for the hydrogen selective catalytic reduction device in the second pipeline to achieve accurate regulation of the hydrogen concentration.

[0077] Furthermore, in one embodiment, the hydrogen fuel engine exhaust post-treatment method further comprises:

[0078] When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the second temperature threshold, and the hydrogen concentration in the exhaust gas after post-processing is greater than the third concentration threshold, the hydrogen concentration in the exhaust gas before post-processing is lowered.

[0079] In this embodiment, the hydrogen concentration of the exhaust gas after entering the second pipeline for post-treatment is monitored. If the hydrogen concentration is too high, it means that there is an excess of hydrogen participating in the post-treatment. It is necessary to lower the hydrogen concentration in the exhaust gas before participating in the post-treatment until the hydrogen concentration drops to an acceptable range.

[0080] As an optional implementation, the step of lowering the hydrogen concentration in the tail gas before post-treatment includes:

[0081] When 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 first hydrogen injector is a hydrogen injector of a hydrogen fuel engine;

[0082] When the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke ends is equal to zero, the amount of hydrogen injected into the cylinder by the first hydrogen injector before the power stroke starts is reduced.

[0083] In this embodiment, before participating in the post-processing, there are two sources of hydrogen in the exhaust gas, one is a part of the hydrogen injected into the cylinder by the first hydrogen injector before the start of the power stroke, that is, the remaining part of the combustion reaction, and the other is all the hydrogen injected into the cylinder by the first hydrogen injector after the end of the power stroke. Since there are many factors affecting each combustion reaction, it is difficult to accurately control the amount of remaining hydrogen. Therefore, when it is necessary to reduce the hydrogen concentration in the exhaust gas before participating in the post-processing, it is preferred to reduce the amount of hydrogen injected into the cylinder by the first hydrogen injector after the end of the power stroke. After reducing it to zero, the hydrogen injected into the cylinder by the first hydrogen injector before the start of the power stroke is further reduced.

[0084] As an optional implementation, the step of lowering the hydrogen concentration in the tail gas before post-treatment includes:

[0085] When the amount of hydrogen injected into the second pipeline by the second hydrogen injector is greater than zero, the amount of hydrogen injected into the second pipeline by the second hydrogen injector is reduced, wherein the second pipeline is further provided with a second hydrogen injector, and the second hydrogen injector is located upstream of the hydrogen selective catalytic reduction device;

[0086] When the amount of hydrogen injected into the second 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.

[0087] Specifically in this embodiment, the hydrogen injected into the cylinder by the first hydrogen injector before the start of the power stroke will participate in the combustion, and the hydrogen injected into the second pipeline by the second hydrogen injector will not participate in the combustion, so it is preferred to reduce the amount of the former, and after reducing it to zero, the amount of the latter is reduced.

[0088] It can be understood that the above embodiment describes how to reasonably control the amount of hydrogen participating in the post-treatment when the tail gas enters the second pipeline for post-treatment. In fact, when the tail gas enters the first pipeline for post-treatment, it is also necessary to reasonably control the amount of ammonia participating in the post-treatment. Since the ammonia selective catalytic reduction technology is very mature, you can refer to relevant materials and will not elaborate on it here.

[0089] Figure 3 A schematic diagram of the structure of an exhaust gas aftertreatment system for a hydrogen fuel engine in one embodiment of the present application is shown.

[0090] Reference Figure 3 The exhaust aftertreatment 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, a hydrogen selective catalytic reduction device 6, a nitrogen oxide sensor 7 and a hydrogen sensor 8.

[0091] 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 intake port of the intake main pipeline 11 is connected to the outlet of the hydrogen fuel engine (not shown), the outlet of the intake main pipeline 11 is connected to the intake ports of the first parallel pipeline 12 and the second parallel pipeline 13, and the intake port of the outlet main pipeline 14 is connected to the outlet ports of the first parallel pipeline 12 and the second parallel pipeline 13.

[0092] The temperature sensor 2 is arranged on the main air intake line 11. The air intake 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 intake of the first parallel line 12, and the second air outlet of the three-way valve 3 is connected to the air intake of the second parallel line 13.

[0093] The hydrogen-oxygen catalyst 4 is arranged in the first parallel pipeline 12, and the ammonia selective catalytic reduction device 5 is arranged in the first parallel pipeline 12, downstream of the hydrogen-oxygen catalyst 4. The hydrogen selective catalytic reduction device 6 is arranged in the second parallel pipeline 13. The nitrogen oxide sensor 7 is arranged in the outlet main pipeline 14. The hydrogen sensor 8 is arranged in the outlet main pipeline 14.

[0094] 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 to hydrolyze and generate ammonia. The catalyst 52 is used to provide a place for the selective catalytic reduction reaction of ammonia and nitrogen oxides and the necessary catalytic effect. The ammonia slip catalyst 53 is used to remove the excess ammonia that does not participate in the reaction.

[0095] The hydrogen fuel engine exhaust aftertreatment method of the present application is applicable to Figure 3 The exhaust after-treatment system of the hydrogen fuel engine shown uses the first parallel pipeline 12 as the first pipeline and the second parallel pipeline 13 as the second pipeline. The original exhaust temperature of the hydrogen fuel engine is collected by the temperature sensor 2, and the exhaust gas flow to the first pipeline or the second pipeline is controlled by the three-way valve 3. When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the second temperature threshold, the nitrogen oxide concentration in the exhaust gas after the after-treatment is collected by the nitrogen oxide sensor 7, and the hydrogen concentration in the exhaust gas after the after-treatment is collected by the hydrogen sensor 8.

[0096] It should be noted that Figure 3 This is only used as an example of the system structure to facilitate a more intuitive understanding of how the various operations required by the present application can be implemented, but it is not intended to limit the system structure. For example, assuming that the nitrogen oxide sensor and the hydrogen sensor are arranged in the second parallel pipeline 13, located downstream of the hydrogen selective catalytic reduction device 6, the corresponding collection work can also be completed. For another example, the first pipeline and the second pipeline are not necessarily Figure 3 The simple parallel relationship shown.

[0097] In a second aspect, an embodiment of the present application also provides a hydrogen fuel engine exhaust after-treatment device.

[0098] Figure 4 A schematic diagram of the functional modules of an exhaust gas aftertreatment device for a hydrogen fuel engine in one embodiment of the present application is shown.

[0099] Reference Figure 4 In one embodiment, the exhaust gas aftertreatment device of a hydrogen fuel engine comprises:

[0100] A first flow direction control module 10 is used to control the exhaust gas to enter the first pipeline for post-processing when the original exhaust temperature of the hydrogen fuel engine is greater than a first temperature threshold, wherein the first pipeline is provided with a hydrogen-oxygen catalyst and an ammonia selective catalytic reduction device, and the hydrogen-oxygen catalyst is located upstream of the ammonia selective catalytic reduction device;

[0101] The second flow control module 20 is used to control the exhaust gas to enter the second pipeline for post-processing when the original exhaust temperature of the hydrogen fuel engine is less than or equal to the second temperature threshold, wherein the second temperature threshold is less than or equal to the first temperature threshold, and the second pipeline is provided with a hydrogen selective catalytic reduction device.

[0102] Further, in one embodiment, the second temperature threshold is equal to the first temperature threshold;

[0103] The first temperature threshold is the original exhaust temperature when the hydrogen fuel engine is operating at the target operating point;

[0104] Among the different test operating points, the emission quantification value corresponding to the target operating point is the lowest;

[0105] The emission quantification value is the weighted calculation result of the nitrogen oxide concentration and hydrogen concentration in the exhaust gas entering the first pipeline after post-treatment when the hydrogen fuel engine is working at the corresponding test operating point;

[0106] 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 and the reference temperature of the hydrogen fuel engine is less than or equal to the preset span;

[0107] 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.

[0108] Further, in one embodiment, the second temperature threshold is less than the first temperature threshold;

[0109] The hydrogen fuel engine exhaust after-treatment device further includes a third flow direction control module 30, which is used to:

[0110] When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the first temperature threshold and greater than the second temperature threshold, and the hydrogen concentration in the exhaust gas after post-treatment is less than or equal to the first concentration threshold, the exhaust gas is controlled to enter the first pipeline for post-treatment;

[0111] When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the first temperature threshold and greater than the second temperature threshold, and the hydrogen concentration in the exhaust gas after post-processing is greater than the first concentration threshold, the exhaust gas is controlled to enter the second pipeline for post-processing.

[0112] Furthermore, in one embodiment, the exhaust gas aftertreatment device of the hydrogen fuel engine further includes a hydrogen injection control module 40, which is used to:

[0113] When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the second temperature threshold, and the nitrogen oxide concentration in the exhaust gas after post-processing is greater than the second concentration threshold, the hydrogen concentration in the exhaust gas before post-processing is increased.

[0114] Furthermore, in one embodiment, the hydrogen injection control module 40 is used to:

[0115] The amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke is completed is increased, wherein the first hydrogen injector is a hydrogen injector of a hydrogen fuel engine.

[0116] Furthermore, in one embodiment, the hydrogen injection control module 40 is used to:

[0117] The amount of hydrogen injected into the second pipeline by the second hydrogen injector is increased, wherein the second pipeline is further provided with a second hydrogen injector, and the second hydrogen injector is located upstream of the hydrogen selective catalytic reduction device.

[0118] Furthermore, in one embodiment, the exhaust gas aftertreatment device of the hydrogen fuel engine further includes a hydrogen injection control module 40, which is used to:

[0119] When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the second temperature threshold, and the hydrogen concentration in the exhaust gas after post-processing is greater than the third concentration threshold, the hydrogen concentration in the exhaust gas before post-processing is lowered.

[0120] Furthermore, in one embodiment, the hydrogen injection control module 40 is used to:

[0121] When 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 first hydrogen injector is a hydrogen injector of a hydrogen fuel engine;

[0122] When the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke ends is equal to zero, the amount of hydrogen injected into the cylinder by the first hydrogen injector before the power stroke starts is reduced.

[0123] Furthermore, in one embodiment, the hydrogen injection control module 40 is used to:

[0124] When the amount of hydrogen injected into the second pipeline by the second hydrogen injector is greater than zero, the amount of hydrogen injected into the second pipeline by the second hydrogen injector is reduced, wherein the second pipeline is further provided with a second hydrogen injector, and the second hydrogen injector is located upstream of the hydrogen selective catalytic reduction device;

[0125] When the amount of hydrogen injected into the second 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.

[0126] Among them, the functional implementation of each module in the above-mentioned hydrogen fuel engine exhaust gas after-treatment device corresponds to the various steps in the above-mentioned hydrogen fuel engine exhaust gas after-treatment method embodiment, and its functions and implementation processes will not be repeated here one by one.

[0127] It should be noted that the serial numbers of the above-mentioned embodiments of the present application are only for description and do not represent the advantages or disadvantages of the embodiments.

[0128] 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 "first", "second" and "third" to different types.

[0129] In the description of the embodiments of the present application, "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 the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "for example" or "for example" is intended to present related concepts in a specific way.

[0130] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; the “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.

[0131] In some processes described in the embodiments of the present application, multiple operations or steps that appear in a specific order are included, but it should be understood that these operations or steps may not be executed in the order in which they appear in the embodiments of the present application or in parallel, and the sequence number of the operation is only used to distinguish the different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed in sequence or in parallel, and these operations or steps may be combined.

[0132] 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 a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application is essentially 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, disk, CD) as described above, and includes a number of instructions for a terminal device to execute the methods described in each embodiment of the present application.

[0133] The above are only preferred embodiments of the present application, and are not intended to 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 method for post-processing exhaust gas from a hydrogen fuel engine, characterized in that: The hydrogen fuel engine exhaust post-treatment method comprises: When the original exhaust temperature of the hydrogen fuel engine is greater than a first temperature threshold, the exhaust gas is controlled to enter the first pipeline for post-processing, wherein the first pipeline is provided with a hydrogen-oxygen catalyst and an ammonia selective catalytic reduction device, and the hydrogen-oxygen catalyst is located upstream of the ammonia selective catalytic reduction device; When the original exhaust temperature of the hydrogen fuel engine is less than or equal to a second temperature threshold, the exhaust gas is controlled to enter the second pipeline for post-processing, wherein the second temperature threshold is less than or equal to the first temperature threshold, and the second pipeline is provided with a hydrogen selective catalytic reduction device.

2. The method for post-processing exhaust gas from a hydrogen fuel engine according to claim 1, characterized in that: The second temperature threshold is equal to the first temperature threshold; The first temperature threshold is the original exhaust temperature when the hydrogen fuel engine is operating at the target operating point; Among the different test operating points, the emission quantification value corresponding to the target operating point is the lowest; The emission quantification value is the weighted calculation result of the nitrogen oxide concentration and hydrogen concentration in the exhaust gas entering the first pipeline after post-treatment when the hydrogen fuel engine is working at the corresponding test operating point; 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 and the reference temperature of the hydrogen fuel engine is less than or equal to the preset span; 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.

3. The method for post-processing exhaust gas from a hydrogen fuel engine according to claim 1, characterized in that: The second temperature threshold is less than the first temperature threshold; The hydrogen fuel engine exhaust post-treatment method further comprises: When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the first temperature threshold and greater than the second temperature threshold, and the hydrogen concentration in the exhaust gas after post-treatment is less than or equal to the first concentration threshold, the exhaust gas is controlled to enter the first pipeline for post-treatment; When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the first temperature threshold and greater than the second temperature threshold, and the hydrogen concentration in the exhaust gas after post-processing is greater than the first concentration threshold, the exhaust gas is controlled to enter the second pipeline for post-processing.

4. The method for post-processing exhaust gas from a hydrogen fuel engine according to any one of claims 1 to 3, characterized in that: The hydrogen fuel engine exhaust post-treatment method further comprises: When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the second temperature threshold, and the nitrogen oxide concentration in the exhaust gas after post-processing is greater than the second concentration threshold, the hydrogen concentration in the exhaust gas before post-processing is increased.

5. The method for post-processing exhaust gas from a hydrogen fuel engine as claimed in claim 4, characterized in that: The step of increasing the hydrogen concentration in the tail gas before post-treatment comprises: The amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke is completed is increased, wherein the first hydrogen injector is a hydrogen injector of a hydrogen fuel engine.

6. The method for post-processing exhaust gas from a hydrogen fuel engine according to claim 4, characterized in that: The step of increasing the hydrogen concentration in the tail gas before post-treatment comprises: The amount of hydrogen injected into the second pipeline by the second hydrogen injector is increased, wherein the second pipeline is further provided with a second hydrogen injector, and the second hydrogen injector is located upstream of the hydrogen selective catalytic reduction device.

7. The method for post-processing exhaust gas from a hydrogen fuel engine according to any one of claims 1 to 3, characterized in that: The hydrogen fuel engine exhaust post-treatment method further comprises: When the original exhaust temperature of the hydrogen fuel engine is less than or equal to the second temperature threshold, and the hydrogen concentration in the exhaust gas after post-processing is greater than the third concentration threshold, the hydrogen concentration in the exhaust gas before post-processing is lowered.

8. The method for post-processing exhaust gas from a hydrogen fuel engine as claimed in claim 7, characterized in that: The step of lowering the hydrogen concentration in the tail gas before post-treatment comprises: When 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 first hydrogen injector is a hydrogen injector of a hydrogen fuel engine; When the amount of hydrogen injected into the cylinder by the first hydrogen injector after the power stroke ends is equal to zero, the amount of hydrogen injected into the cylinder by the first hydrogen injector before the power stroke starts is reduced.

9. The method for post-processing exhaust gas from a hydrogen fuel engine according to claim 7, characterized in that: The step of lowering the hydrogen concentration in the tail gas before post-treatment comprises: When the amount of hydrogen injected into the second pipeline by the second hydrogen injector is greater than zero, the amount of hydrogen injected into the second pipeline by the second hydrogen injector is reduced, wherein the second pipeline is further provided with a second hydrogen injector, and the second hydrogen injector is located upstream of the hydrogen selective catalytic reduction device; When the amount of hydrogen injected into the second 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.

10. A hydrogen fuel engine exhaust aftertreatment device, characterized in that: The hydrogen fuel engine exhaust after-treatment device comprises: A first flow direction control module, used for controlling the exhaust gas to enter the first pipeline for post-processing when the original exhaust temperature of the hydrogen fuel engine is greater than a first temperature threshold, wherein the first pipeline is provided with a hydrogen-oxygen catalyst and an ammonia selective catalytic reduction device, and the hydrogen-oxygen catalyst is located upstream of the ammonia selective catalytic reduction device; The second flow direction control module is used to control the exhaust gas to enter the second pipeline for post-processing when the original exhaust temperature of the hydrogen fuel engine is less than or equal to the second temperature threshold, wherein the second temperature threshold is less than or equal to the first temperature threshold, and the second pipeline is provided with a hydrogen selective catalytic reduction device.

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