Hydrogen fuel engine tail gas aftertreatment system and method

Abstract

The invention provides a hydrogen fuel engine tail gas after-treatment system and method.The system comprises a tail gas pipeline, a first parallel pipeline, a second parallel pipeline and a gas outlet main pipeline, and a gas inlet of the gas inlet main pipeline communicates with a gas outlet of a hydrogen fuel engine; the temperature sensor is arranged on the air inlet main pipeline; an air inlet of the three-way valve is communicated with an air outlet of the air inlet main pipeline, a first air outlet of the three-way valve is communicated with an air inlet of the first parallel pipeline, and a second air outlet of the three-way valve is communicated with an air inlet of the second parallel pipeline; the hydrogen-oxygen catalyst is arranged on the first parallel pipeline; the ammonia selective catalytic reduction device is arranged on the first parallel pipeline and is positioned at the downstream of the hydrogen-oxygen catalyst; and the hydrogen selective catalytic reduction device is arranged on the second parallel pipeline. 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 system and method for exhaust gas aftertreatment of 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 hydrogen fuel engine exhaust after-treatment system and method, which can solve the technical problem in the prior art that nitrogen oxide and hydrogen emissions under all operating conditions cannot be effectively suppressed.

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

[0006] The tail gas pipeline comprises an air intake main pipeline, a first parallel pipeline, a second parallel pipeline and an air outlet main pipeline, wherein the air intake of the air intake main pipeline is connected to the air outlet of the hydrogen fuel engine, the air outlet of the air intake main pipeline is connected to the air intakes of the first parallel pipeline and the second parallel pipeline, and the air intake of the air outlet main pipeline is connected to the air outlets of the first parallel pipeline and the second parallel pipeline;

[0007] A temperature sensor is arranged 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 is arranged in the first parallel pipeline;

[0010] an ammonia selective catalytic reduction device, arranged 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 arranged 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 exhaust gas after-treatment system of the hydrogen fuel engine. 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 the first temperature threshold, the first gas outlet of the three-way valve is opened, the second gas 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-treatment method further comprises:

[0023] 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 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, 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-treatment method further comprises:

[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-treatment method further comprises:

[0027] 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 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 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-treatment method further comprises:

[0030] 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 greater than zero, the amount of hydrogen injected into the second parallel pipeline 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 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 a 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 a 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 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the structure of a hydrogen fuel engine exhaust gas aftertreatment system in one embodiment of the present application;

[0034] Figure 2 This is a schematic diagram of the structure 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 the exhaust post-treatment method of 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 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

[0039] 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.

[0040] 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.

[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 diagram of the structure of an exhaust gas aftertreatment system for a hydrogen fuel engine in one embodiment of the present application is shown.

[0043] Reference Figure 1 In one embodiment, 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 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 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.

[0045] 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.

[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 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.

[0048] 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] 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. By controlling the first gas outlet of the three-way valve 3 to be opened and the second gas outlet to be closed, the exhaust gas can participate in the post-treatment in the first parallel pipeline 12. The original exhaust temperature can be collected by the temperature sensor 2 as the control basis of the three-way valve, thereby eliminating the low temperature working condition to ensure the conversion efficiency of the exhaust gas when participating in the post-treatment in the first parallel pipeline 12.

[0050] 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.

[0051] By controlling the second outlet of the three-way valve 3 to open and the first outlet to close, the exhaust gas can participate in post-processing in the second parallel pipeline 13. The original exhaust temperature can be collected by the temperature sensor 2 as a control basis for the three-way valve, thereby eliminating high-temperature conditions to ensure 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-processing, the hydrogen in the exhaust gas is first removed by the hydrogen-oxygen catalyst 4, and then the nitrogen oxides in the exhaust gas are removed by the ammonia selective catalytic reduction device 5, which can ensure a high conversion efficiency under medium and high temperature conditions. When the exhaust gas enters the second parallel pipeline 13 for post-processing, the nitrogen oxides and hydrogen in the exhaust gas are removed by the hydrogen selective catalytic reduction device 6, which can ensure a high conversion efficiency under medium and low temperature conditions. The measured value of the temperature sensor 2 can be used as a control basis for the three-way valve 3. Through this embodiment, a reasonable selection of the exhaust gas 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.

[0053] Furthermore, in one embodiment, the 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 participate in post-processing as part of the exhaust gas, thereby achieving precise regulation 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 6, which helps to simplify the structure and reduce costs.

[0055] Furthermore, in one embodiment, the exhaust aftertreatment system of the hydrogen fuel engine 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 accurate regulation of the hydrogen concentration.

[0057] Furthermore, in one embodiment, the exhaust after-treatment system of the hydrogen fuel engine also includes a nitrogen oxide sensor, which is arranged in the 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 feedback adjusting the hydrogen injection amount of the first hydrogen injector or the second hydrogen injector.

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

[0060] Figure 2 A schematic structural diagram of an exhaust gas aftertreatment 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 , so that 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-treatment, thereby feedback-adjusting the urea injection amount of the urea injector 51 .

[0062] Furthermore, in one embodiment, the exhaust gas after-treatment system of the hydrogen fuel engine also includes a hydrogen sensor, which is arranged in the 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-treatment, thereby feedback adjusting 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 . Thus, 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 , the exhaust aftertreatment method of hydrogen fuel engine includes:

[0068] S1. When the measured value of the temperature sensor 2 is greater than the first temperature 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;

[0069] S2. When the measured 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 the temperature sensor 2 (i.e., the original exhaust temperature of the hydrogen fuel engine) is the only basis for selecting the exhaust gas post-treatment method. Considering that there is a certain temperature range, the conversion efficiency of the two exhaust gas post-treatment 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 measured value of the temperature sensor 2 is less than or equal to the first temperature threshold and greater than the second temperature threshold, any exhaust gas post-treatment method can be used, and other bases can also be introduced for selection.

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

[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 completed 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 measurement value of the nitrogen oxide sensor is too high, indicating that there is insufficient hydrogen in the second parallel pipeline 13 for post-processing, and 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 elaborated here.

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

[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, the measurement value of the nitrogen oxide sensor is too high, which 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 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 elaborated here.

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

[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, if the measured value of the hydrogen sensor is too high, it means that there is too much hydrogen in the second parallel pipeline 13 that participates in the post-processing, and it is necessary to reduce the hydrogen concentration in the tail gas before participating in the post-processing until the hydrogen concentration is reduced to an acceptable range. Before participating in the post-processing, there are two sources of hydrogen in the tail 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, the amount of remaining hydrogen is difficult to accurately control. Therefore, when it is necessary to reduce the hydrogen concentration in the tail 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 amount of hydrogen injected into the cylinder by the first hydrogen injector before the start of the power stroke is further reduced.

[0084] The relevant description of the first hydrogen injector and the hydrogen sensor refers to the above embodiments and will not be elaborated here.

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

[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 disposed 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 pipeline 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 a hydrogen injector of a hydrogen fuel engine.

[0088] In this embodiment, if the measured value of the hydrogen sensor is too high, it means that there is too much hydrogen in the second parallel pipeline 13 for post-processing, and it is necessary to reduce the hydrogen concentration in the tail gas before participating in the post-processing until the hydrogen concentration is reduced to an acceptable range. Before participating in the post-processing, there are two sources of hydrogen in the tail 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 second parallel pipeline 13 by the second hydrogen injector. 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 tail 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 amount of hydrogen injected into the second parallel pipeline 13 by the second hydrogen injector is 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 elaborated here.

[0090] 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 parallel pipeline 13 for post-treatment. In fact, when the tail gas enters the first parallel pipeline 12 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.

[0091] Further, 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 the hydrogen concentration in the exhaust gas after post-treatment in the first parallel pipeline 12 when the hydrogen fuel engine is working 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 and the reference temperature of the hydrogen fuel engine 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 measured value of the temperature sensor 2 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.

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

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

[0101] When the measured value of the temperature sensor 2 is less than or equal to the first temperature threshold value and greater than the second temperature threshold value, and the measured value of the hydrogen sensor is less than or equal to the third concentration threshold value, 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 less than the first temperature threshold. When the measured value of the temperature sensor 2 is less than or equal to the first temperature threshold and greater than the second temperature threshold, the measured value of the hydrogen sensor is introduced as an additional reference. When the measured value of the hydrogen sensor is high, it is considered that the first parallel pipeline 12 cannot effectively control hydrogen emissions, and it is necessary to use the second parallel pipeline 13 for tail gas post-treatment. Through this embodiment, the tail gas 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.

[0104] Specifically, it is arranged in the downstream pipeline of the ammonia selective catalytic reduction device 5 , that is, arranged in the first parallel pipeline 12 and located downstream of the ammonia selective catalytic reduction device 5 , or arranged 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 only for description and do not represent the advantages or disadvantages of the embodiments.

[0107] In the description of the present application, it should be noted that the terms "upper", "lower", etc. 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 the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present 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 it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present 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 "first", "second" and "third" to different types.

[0109] 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.

[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; 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.

[0111] 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.

[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 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.

[0113] 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 hydrogen fuel engine exhaust after-treatment system, characterized in that: The hydrogen fuel engine exhaust after-treatment system comprises: The tail gas pipeline comprises an air intake main pipeline, a first parallel pipeline, a second parallel pipeline and an air outlet main pipeline, wherein the air intake of the air intake main pipeline is connected to the air outlet of the hydrogen fuel engine, the air outlet of the air intake main pipeline is connected to the air intakes of the first parallel pipeline and the second parallel pipeline, and the air intake of the air outlet main pipeline is connected to the air outlets of the first parallel pipeline and the second parallel pipeline; A temperature sensor is arranged 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 is 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 The hydrogen selective catalytic reduction device is arranged in the second parallel pipeline.

2. The hydrogen fuel engine exhaust after-treatment system according to claim 1, characterized in that: The first hydrogen injector is configured to inject hydrogen into the cylinder after the power stroke ends. The first hydrogen injector is a hydrogen injector of a hydrogen fuel engine.

3. The hydrogen fuel engine exhaust after-treatment system according to claim 1, characterized in that: The hydrogen fuel engine exhaust after-treatment system also includes: The second hydrogen injector is arranged in the second parallel pipeline and is located upstream of the hydrogen selective catalytic reduction device.

4. The hydrogen fuel engine exhaust after-treatment system according to claim 2 or 3, characterized in that: The hydrogen fuel engine exhaust after-treatment system also includes: The nitrogen oxide sensor is arranged in the downstream pipeline of the hydrogen selective catalytic reduction device.

5. The hydrogen fuel engine exhaust after-treatment system according to claim 2 or 3, characterized in that: The hydrogen fuel engine exhaust after-treatment system also includes: The hydrogen sensor is arranged in the downstream pipeline of the hydrogen selective catalytic reduction device.

6. A method for post-processing exhaust gas from a hydrogen fuel engine, characterized in that: The exhaust gas after-treatment system of a hydrogen fuel engine according to any one of claims 1 to 5, wherein the exhaust gas after-treatment method of the hydrogen fuel engine comprises: When the measured value of the temperature sensor is greater than the first temperature threshold, the first gas outlet of the three-way valve is opened, the second gas 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 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.

7. The method for post-processing exhaust gas from a hydrogen fuel engine as claimed in claim 6, characterized in that: The hydrogen fuel engine exhaust post-treatment method further comprises: 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 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, and the nitrogen oxide sensor is arranged in a downstream pipeline of the hydrogen selective catalytic reduction device.

8. The method for post-processing exhaust gas from a hydrogen fuel engine as claimed in claim 6, characterized in that: The hydrogen fuel engine exhaust post-treatment method further comprises: 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.

9. The method for post-processing exhaust gas from a hydrogen fuel engine according to claim 6, characterized in that: The hydrogen fuel engine exhaust post-treatment method further comprises: 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 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 a 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.

10. The method for post-processing exhaust gas from a hydrogen fuel engine according to claim 6, characterized in that: The hydrogen fuel engine exhaust post-treatment method further comprises: 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 greater than zero, the amount of hydrogen injected into the second parallel pipeline 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 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 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.

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