Urea crystallization control method and device for post-treatment system and post-treatment system

Abstract

The invention provides a urea crystallization control method and device for an after-treatment system and the after-treatment system. The technical problems that in the prior art, whole vehicle arrangement is difficult, crystallization of a mixer is too much, the SCR catalytic conversion efficiency is reduced, and nitrogen oxide discharged from tail gas is likely to be increased are solved. According to the urea crystallization control method for the post-treatment system, the temperature and the waste gas mass flow in front of the first nitrogen oxide treatment device and the preceding-stage urea injection amount of the preceding-stage urea mixer are obtained, and the urea crystallization of the post-treatment system is controlled according to the temperature and the waste gas mass flow in front of the first nitrogen oxide treatment device and the preceding-stage urea injection amount of the preceding-stage urea mixer. And calculating the urea crystallization amount of the preceding-stage urea mixer, and performing hierarchical control on the crystallization amount according to the urea crystallization amount of the preceding-stage urea mixer. On the basis of the existing post-treatment arrangement space, the crystallization amount of the preceding-stage urea mixer can be subjected to hierarchical control, so that the arrangement difficulty of the whole vehicle is reduced, and emission of nitric oxide and particulate matter is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile exhaust emission, in particular to a post-processing system urea crystallization control method and device and a post-processing system. BACKGROUND

[0002] With the development of the national seven-stage emission regulations, the emission of nitrogen oxides and particulate matter is further strictly required. The arrangement space of the national six-stage post-processing has been fixed, and the re-arrangement of the post-processing space not only greatly increases the development cost, but also may cause installation difficulties due to the large volume of the newly developed post-processing space. In addition, there is a problem that too much crystallization of the mixer reduces the efficiency of the SCR catalytic conversion, which easily leads to an increase in the emission of nitrogen oxides.

[0003] In the prior art, the front-stage urea mixer A1 is usually arranged on the pipeline at the outlet of the engine turbine, and the urea injection is also after the turbine. Since the mixed gas is a certain distance away from the post-processing box, the mixer is simple and not easy to crystallize, which can reduce the emission of nitrogen oxides, but the arrangement of the mixer is difficult, thereby increasing the vehicle arrangement difficulty, and the arrangement still needs to be adjusted separately for different vehicle models.

[0004] Therefore, it is necessary to provide a post-processing system urea crystallization control method which can be implemented on the basis of the existing national six-stage post-processing arrangement space, the vehicle arrangement is simple, and the emission of nitrogen oxides and particulate matter can be reduced. SUMMARY

[0005] Therefore, the present application provides a post-processing system urea crystallization control method and device, a post-processing system and a vehicle. On the basis of the existing post-processing arrangement space, the crystallization amount is controlled in stages according to the urea crystallization amount of the front-stage urea mixer, so as to reduce the vehicle arrangement difficulty and reduce the emission of nitrogen oxides and particulate matter.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme: a post-processing system urea crystallization control method, the control method is applicable to a post-processing system, the post-processing system comprises: a front-stage urea mixer, which sprays front-stage urea and mixes the sprayed urea with exhaust gas; a first nitrogen oxide treatment device, which adopts a reducing catalyst and an oxidizing catalyst, reduces nitrogen oxides by using the front-stage urea sprayed by the front-stage urea mixer, and oxidizes ammonia; a particulate treatment device, which adopts an oxidizing catalyst to capture particulate matter and nitrogen oxides; a rear-stage urea mixer, which mixes rear-stage urea sprayed after the particulate treatment device with exhaust gas; and a second nitrogen oxide treatment device, which adopts a reducing catalyst and an oxidizing catalyst, reduces nitrogen oxides by using the urea sprayed after the particulate treatment device, and oxidizes ammonia. The control method comprises: Acquiring the temperature and exhaust gas mass flow rate before the first nitrogen oxide treatment device, and the pre-stage urea injection amount of the pre-stage urea mixer; calculating the amount of urea crystals in the front-stage urea mixer according to the temperature before the first nitrogen oxide treatment device, the exhaust gas mass flow rate, and the front-stage urea injection amount of the front-stage urea mixer; The amount of urea crystals is controlled in stages according to the amount of urea crystals in the preceding urea mixer.

[0007] In one embodiment of the present application, obtaining the temperature before the first nitrogen oxide treatment device includes: Acquiring the temperature and exhaust gas mass flow rate before the front-stage urea mixer, and the front-stage urea injection amount of the front-stage urea mixer; The temperature before the first nitrogen oxide treatment device is calculated according to the temperature before the front-stage urea mixer, the exhaust gas mass flow rate, and the front-stage urea injection amount of the front-stage urea mixer.

[0008] In one embodiment of the present application, the amount of urea crystallization is controlled in stages according to the amount of urea crystallization in the preceding urea mixer, including: When the amount of urea crystals in the front-stage urea mixer is greater than or equal to a first preset threshold, the front-stage urea injection amount is controlled to decrease, and the rear-stage urea injection amount is controlled to increase.

[0009] In one embodiment of the present application, the control method further includes: When the crystallization amount is less than or equal to a second preset threshold, the graded control of the crystallization amount is exited, wherein the first preset threshold is greater than the second preset threshold.

[0010] In one embodiment of the present application, the amount of urea crystals is controlled in stages according to the amount of urea crystals in the preceding urea mixer, further comprising: When the amount of urea crystals in the front-stage urea mixer is greater than or equal to a third preset threshold, the engine thermal management system is started to increase the temperature before the front-stage urea mixer, wherein the third preset threshold is greater than the first preset threshold.

[0011] In one embodiment of the present application, the control method further includes: When the crystallization amount is less than or equal to a fourth preset threshold, the graded control of the crystallization amount is exited, wherein the third preset threshold is greater than the fourth preset threshold.

[0012] In one embodiment of the present application, obtaining the pre-stage urea injection amount of the pre-stage urea mixer includes: obtaining a temperature after the first nitrogen oxide treatment device; calculating an average temperature of the first nitrogen oxide treatment device according to a temperature before the first nitrogen oxide treatment device and a temperature after the first nitrogen oxide treatment device; determining a nitrogen oxide conversion efficiency based on a mapping relationship between an average temperature and a space velocity of the first nitrogen oxide treatment device; The pre-stage urea injection amount of the pre-stage urea mixer is calculated according to the exhaust gas mass flow, the nitrogen oxide concentration before the pre-stage urea mixer, and the nitrogen oxide conversion efficiency.

[0013] As a second aspect of the present application, the present application further provides a urea crystallization control device for a post-treatment system, comprising: A data acquisition module, used to obtain the temperature and exhaust gas mass flow rate before the first nitrogen oxide treatment device, and the pre-stage urea injection amount of the pre-stage urea mixer; a calculation module for calculating the amount of urea crystals in the front-stage urea mixer according to the temperature before the first nitrogen oxide treatment device, the exhaust gas mass flow rate, and the front-stage urea injection amount of the front-stage urea mixer; The control module is used to perform graded control on the amount of urea crystals according to the amount of urea crystals in the preceding urea mixer.

[0014] As a third aspect of the present application, the present application further provides a post-processing system, comprising: a pre-stage urea mixer, which injects pre-stage urea and mixes the injected urea with the exhaust gas; The first nitrogen oxide treatment device uses a reducing catalyst and an oxidizing catalyst to reduce nitrogen oxides and oxidize ammonia using the pre-stage urea injected from the pre-stage urea mixer; A particulate matter processor uses an oxidizing catalyst to capture particulates and nitrogen oxides; A post-stage urea mixer, which mixes the post-stage urea injected after the particle treatment device with the exhaust gas; A second nitrogen oxide treatment device employs a reducing catalyst and an oxidizing catalyst, utilizing urea injected after the particulate treatment device to reduce nitrogen oxides and oxidize ammonia; The controller is configured to obtain a temperature before a first nitrogen oxide treatment device, an exhaust gas mass flow rate, and a pre-stage urea injection amount of a pre-stage urea mixer; calculate a urea crystallization amount of the pre-stage urea mixer based on the temperature before the first nitrogen oxide treatment device, the exhaust gas mass flow rate, and the pre-stage urea injection amount of the pre-stage urea mixer; and perform graded control on the crystallization amount based on the urea crystallization amount of the pre-stage urea mixer.

[0015] As a fourth aspect of the present application, the present application further provides a vehicle, comprising: The post-processing system described in the third aspect above; The present application provides a method for controlling urea crystallization in a post-treatment system, which is applicable to a post-treatment system. The post-treatment system includes, in sequence: a front-stage urea mixer, a first nitrogen oxide treatment device, a particle treatment device, a rear-stage urea mixer, and a second nitrogen oxide treatment device. Without changing the layout space of the original post-treatment, the layout position of the front-stage urea mixer is changed, and the front-stage urea is injected into the front-stage urea mixer to achieve mixing of urea and exhaust gas, thereby reducing the difficulty of mixer layout, thereby reducing the difficulty of vehicle layout, and being applicable to the layout of different vehicle models. In addition, by obtaining the temperature and exhaust gas mass flow rate before the first nitrogen oxide treatment device, and the front-stage urea injection amount of the front-stage urea mixer, the urea crystallization amount of the front-stage urea mixer is calculated, and the crystallization amount is controlled in stages to improve the efficiency of SCR catalytic conversion, thereby reducing the emission of nitrogen oxides and particulate matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without any creative work.

[0017] Figure 1 A schematic structural diagram of a post-processing system provided in an embodiment of the present application.

[0018] Figure 2 A schematic flow chart of a urea crystallization control method for a post-treatment system provided in one embodiment of the present application.

[0019] Figure 3 A flow chart of a method for obtaining the temperature before a first nitrogen oxide treatment device provided in one embodiment of the present application.

[0020] Figure 4 A schematic flow chart of a method for obtaining a pre-stage urea injection amount of a pre-stage urea mixer provided in one embodiment of the present application.

[0021] Figure 5 A schematic flow chart of a urea crystallization control method for a post-treatment system provided in another embodiment of the present application.

[0022] Figure 6 A schematic flow chart of a urea crystallization control method for a post-treatment system provided in another embodiment of the present application.

[0023] Figure 7 A schematic flow chart of a urea crystallization control method for a post-treatment system provided in another embodiment of the present application.

[0024] Figure 8A schematic flow chart of a urea crystallization control method for a post-treatment system provided in another embodiment of the present application.

[0025] Figure 9 This is a structural schematic diagram of a urea crystallization control device for a post-treatment system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0027] For ease of description, some nouns or terms involved in the embodiments of the present invention are explained below: DPF: (diesel particulate filter, particulate matter trap), used to capture particulate matter in exhaust gas. When the mass of captured particulate matter reaches a certain level, passive regeneration or active regeneration is required to restore the DPF's ability to capture particulate matter.

[0028] The working principle of DPF active regeneration (high temperature regeneration) is to raise the DPF temperature to about 600°C and use the carbon in the DPF to react with oxygen to achieve the purpose of eliminating DPF carbon.

[0029] Reaction principle in DPF: The working principle of DPF passive regeneration is: using the principle of NO2 reacting with carbon in DPF, NO2 has a strong oxidizing ability on the captured particulate matter (carbon), and using the NO2 generated by the front DOC as an oxidant to remove the particulates in the particulate filter and generate CO2, and NO2 is reduced to NO, thereby achieving the purpose of removing particulate matter.

[0030] Reaction principle in DPF: DOC: (diesel oxide catalyst, oxidation catalytic converter), installed in front of DPF, used to convert NO in exhaust gas into NO2, while increasing the exhaust gas temperature, assisting the normal operation of DPF and SCR (selectively catalytic reduction, selective catalytic conversion device).

[0031] Reaction principle within DOC: DDPF: An integrated oxidation trap that is coated with DOC-formulated catalysts and DPF-formulated catalysts in separate areas, taking into account the functions of both DPF and DOC.

[0032] Exemplary Systems As a first aspect of the present application, the present application provides a post-processing system, Figure 1 FIG. 1 is a schematic diagram of a post-processing system according to an embodiment of the present application. Figure 1 As shown, the processing system provided by this application includes: The front-stage urea mixer A1 includes a urea nozzle Inj1 , which is used to inject front-stage urea and mix the injected urea with the exhaust gas to form a uniform mixed gas.

[0033] The first nitrogen oxide treatment device A2 may include a selective catalytic converter SCR and an ammonia slip trap ASC, and uses a reducing catalyst and an oxidizing catalyst to reduce nitrogen oxides NOx and oxidize excess ammonia NH3 using the pre-stage urea injected by the pre-stage urea mixer.

[0034] The particulate matter treatment device A3 uses an oxidizing catalyst to capture particulate matter and nitrogen oxides. The particulate matter treatment device A3 may include an oxidizing catalytic converter DOC and a particulate matter trap DPF.

[0035] The post-stage urea mixer A4 is provided with a urea nozzle Inj2 after the particle treatment device A3 and before the post-stage urea mixer A4. The post-stage urea mixer A4 mixes the post-stage urea injected after the particle treatment device with the exhaust gas to form a uniform mixed gas.

[0036] The second nitrogen oxide treatment device A5 may include a selective catalytic converter SCR and an ammonia slip trap ASC, using a reducing catalyst and an oxidizing catalyst, and utilizing urea injected after the particulate treatment device to reduce nitrogen oxides NOx and oxidize excess ammonia NH3.

[0037] The controller is configured to obtain a temperature before the first nitrogen oxide treatment device A2, an exhaust gas mass flow rate, and a pre-stage urea injection amount of the pre-stage urea mixer, calculate a urea crystallization amount of the pre-stage urea mixer A1 based on the temperature before the first nitrogen oxide treatment device A2, the exhaust gas mass flow rate, and the pre-stage urea injection amount of the pre-stage urea mixer, and perform graded control of the crystallization amount based on the urea crystallization amount of the pre-stage urea mixer A1.

[0038] In one embodiment of the present application, the above-mentioned post-treatment system may further include a temperature sensor for detecting the temperature of the exhaust gas at different stages, such as Figure 1As shown, the first temperature sensor T1 arranged before the front-stage urea mixer A1 can detect the first temperature of the exhaust gas before the front-stage urea mixer A1; the second temperature sensor T2 arranged between the first nitrogen oxide treatment device A2 and the particulate treatment device A3 can detect the second temperature of the exhaust gas after the first nitrogen oxide treatment device A2; the third temperature sensor T3 arranged after the particulate treatment device A3 can detect the third temperature of the exhaust gas after the particulate treatment device A3.

[0039] In one embodiment of the present application, the post-treatment system may further include a nitrogen oxide sensor for detecting the concentration of nitrogen oxides NOx in the exhaust gas at different stages, such as Figure 1 As shown, the first nitrogen oxide sensor N1 arranged before the front-stage urea mixer A1 can detect the first nitrogen oxide concentration of the exhaust gas before the front-stage urea mixer A1; the second nitrogen oxide sensor N2 arranged between the first nitrogen oxide treatment device A2 and the particulate treatment device A3 can detect the second nitrogen oxide concentration of the exhaust gas before the particulate treatment device A3; the third nitrogen oxide sensor N3 arranged after the second nitrogen oxide treatment device A5 can detect the third nitrogen oxide concentration of the exhaust gas after the second nitrogen oxide treatment device A5.

[0040] The post-treatment system provided in this application significantly reduces the difficulty of mixer placement by post-locating the pre-stage urea mixer A1 and the urea nozzle. This significantly reduces the difficulty of mixer placement compared to the prior art, where the pre-stage urea mixer A1 is placed in the pipeline at the engine turbine outlet and urea injection is also placed after the turbine. This reduces the difficulty of mixer placement, thereby reducing the difficulty of vehicle layout and making it suitable for different vehicle models. In addition, by calculating the amount of urea crystals in the pre-stage urea mixer, the amount of crystals is graded and controlled based on the amount of urea crystals in the pre-stage urea mixer A1, so that the amount of urea crystals in the pre-stage urea mixer A1 is controlled within a preset range, thereby improving the efficiency of SCR catalytic conversion and reducing emissions of nitrogen oxides and particulate matter.

[0041] Exemplary Methods As a second aspect of the present application, the present application also provides a post-processing system urea crystallization control method for controlling Figure 1 The aftertreatment system shown, Figure 2 FIG. 1 is a flow chart of a urea crystallization control method for a post-processing system according to an embodiment of the present application. Figure 2 As shown, a method for controlling urea crystallization in a post-treatment system comprises the following steps: S10: Acquire the temperature and exhaust gas mass flow rate before the first nitrogen oxide treatment device, and the pre-stage urea injection amount of the pre-stage urea mixer.

[0042] The temperature before the first nitrogen oxide treatment device A2, the exhaust gas mass flow before the first nitrogen oxide treatment device A2, and the pre-stage urea injection amount of the pre-stage urea mixer A1 are acquired respectively.

[0043] S20: According to the temperature before the first nitrogen oxide treatment device and the exhaust gas mass flow, the pre-stage urea injection amount of the pre-stage urea mixer, the urea crystallization amount of the pre-stage urea mixer is calculated.

[0044] After the temperature before the first nitrogen oxide treatment device A2, the exhaust gas mass flow before the first nitrogen oxide treatment device A2, and the pre-stage urea injection amount of the pre-stage urea mixer A1 are determined, the urea crystallization amount of the pre-stage urea mixer A1 can be calculated according to the temperature before the first nitrogen oxide treatment device A2, the exhaust gas mass flow before the first nitrogen oxide treatment device A2, and the pre-stage urea injection amount of the pre-stage urea mixer A1.

[0045] The specific calculation formula of the urea crystallization amount m of the pre-stage urea mixer A1 is shown in Formula One: Formula One Wherein, m: urea crystallization amount, g; : urea flow, kg / s; : exhaust gas mass flow, kg / s; : crystallization amount generation coefficient based on flow and temperature; : crystallization conversion coefficient based on current crystallization amount and temperature; T20: temperature before the first nitrogen oxide treatment device A2; : interval time.

[0046] S30: According to the urea crystallization amount of the pre-stage urea mixer, the crystallization amount is controlled in stages.

[0047] With the accumulation of time, the urea crystallization amount of the pre-stage urea mixer A1 will be more and more, and when the urea crystallization amount of the pre-stage urea mixer A1 is relatively large, the efficiency of the SCR catalytic conversion in the first nitrogen oxide treatment device A2 will be reduced, which will lead to the increase of the nitrogen oxide emission of the exhaust gas of the first nitrogen oxide treatment device A2, and ultimately the nitrogen oxide emission of the exhaust gas of the second nitrogen oxide treatment device A5 in the aftertreatment system will not meet the standard.

[0048] The present application calculates the urea crystal amount of the front-stage urea mixer A1 and sets a urea crystal amount threshold. By comparing the urea crystal amount with the threshold, it is determined whether the urea crystal amount of the front-stage urea mixer A1 exceeds the standard. In this way, the urea crystal amount is controlled in stages, so that the urea crystal amount of the front-stage urea mixer A1 is controlled within a preset range.

[0049] In one embodiment of the present application, the temperature and exhaust gas mass flow rate before the first nitrogen oxide treatment device A2, and the pre-stage urea injection amount of the pre-stage urea mixer A1 are obtained. The urea crystallization amount of the pre-stage urea mixer is calculated based on the temperature and exhaust gas mass flow rate before the first nitrogen oxide treatment device A2 and the pre-stage urea injection amount of the pre-stage urea mixer A1. The crystallization amount is controlled in stages based on the urea crystallization amount of the pre-stage urea mixer A1, so that the urea crystallization amount of the pre-stage urea mixer A1 is controlled within a preset range, thereby improving the efficiency of the SCR catalytic conversion, thereby reducing the emissions of nitrogen oxides and particulate matter.

[0050] In one embodiment of the present application, Figure 3 As shown, in S10, the temperature before the first nitrogen oxide treatment device is obtained, and the specific steps may include: S211: Acquire the temperature and exhaust gas mass flow rate before the front-stage urea mixer, and the front-stage urea injection amount of the front-stage urea mixer.

[0051] The temperature before the front-stage urea mixer A1, the exhaust gas mass flow before the front-stage urea mixer A1, and the front-stage urea injection amount of the front-stage urea mixer A1 are obtained respectively. Specifically, the temperature before the front-stage urea mixer A1 can be obtained by obtaining the first temperature sensor T1 set before the front-stage urea mixer A1. The exhaust gas mass flow is related to the air intake volume and the fuel amount. Specifically, the theoretical maximum air mass refers to the air mass that the cylinder working volume can accommodate under the intake manifold temperature and pressure. According to the intake manifold temperature and pressure sensor values, the engine speed, the theoretical air mass can be calculated, and the filling coefficient is calibrated at the same time to calculate the actual intake volume, wherein the filling coefficient refers to the ratio of the actual fresh air mass entering the cylinder to the theoretical maximum air mass. The fuel amount is determined according to the injection amount required by the ECU. The specific calculation formula for the exhaust gas mass flow is shown in Formula 2: Air=P / (RT)*V*n / 2*eff Formula 2 Where, P / (RT): ideal gas equation, calculates the air density at the intake manifold state; V*n / 2: The product of engine displacement and speed, used to calculate the volume flow rate of air at this speed; eff: filling coefficient; The specific method of obtaining the pre-stage urea injection amount of the pre-stage urea mixer will be described in detail later.

[0052] S212: Calculate the temperature before the first nitrogen oxide treatment device according to the temperature before the front-stage urea mixer, the exhaust gas mass flow rate, and the front-stage urea injection amount of the front-stage urea mixer.

[0053] After determining the temperature before the front-stage urea mixer A1, the exhaust gas mass flow rate before the front-stage urea mixer A1, and the front-stage urea injection amount of the front-stage urea mixer A1, the temperature before the first nitrogen oxide treatment device A2 can be calculated based on the temperature before the front-stage urea mixer A1, the exhaust gas mass flow rate before the front-stage urea mixer A1, and the front-stage urea injection amount of the front-stage urea mixer A1.

[0054] The specific calculation formula of the temperature T20 before the first nitrogen oxide treatment device A2 is shown in Formula 3: Formula 3 in, : specific heat capacity of urea, J / kg / k; : urea flow rate, kg / s; T0: urea temperature, k; : specific heat capacity of exhaust gas, J / kg / k; : exhaust gas mass flow rate, kg / s; : latent heat of vaporization of water, J / mol; : molar mass of water, kg / mol; : molar mass of urea, kg / mol; : Gibbs free energy of urea decomposition, J / mol.

[0055] In one embodiment of the present application, Figure 4 As shown, in S10, the pre-stage urea injection amount of the pre-stage urea mixer is obtained, and the specific steps may include: S221: Acquire the temperature after the first nitrogen oxide treatment device.

[0056] Specifically, the temperature after the first nitrogen oxide treatment device A2 can be obtained by acquiring the second temperature sensor T2 provided after the first nitrogen oxide treatment device A2.

[0057] S222: Calculate the average temperature of the first nitrogen oxide treatment device according to the temperature before the first nitrogen oxide treatment device and the temperature after the first nitrogen oxide treatment device.

[0058] After determining the temperature before the first nitrogen oxide treatment device A2 and the temperature after the first nitrogen oxide treatment device A2, the average temperature T of the first nitrogen oxide treatment device A2 can be calculated based on the temperature T20 before the first nitrogen oxide treatment device A2 and the temperature T2 after the first nitrogen oxide treatment device A2, where T=(T20+T2) / 2.

[0059] S223: Determine the nitrogen oxide conversion efficiency of the first nitrogen oxide treatment device according to the mapping relationship between the average temperature and the space velocity of the first nitrogen oxide treatment device.

[0060] After determining the average temperature T and air velocity of the first nitrogen oxide treatment device A2, the nitrogen oxide conversion efficiency of the first nitrogen oxide treatment device A2 can be obtained according to the nitrogen oxide conversion efficiency MAP table, wherein the nitrogen oxide conversion efficiency MAP table is obtained by experiments and simulations on the after-treatment system, and includes the relationship between temperature and air velocity and nitrogen oxide conversion efficiency. The average temperature T and air velocity of the first nitrogen oxide treatment device A2 are used as input parameters, and the nitrogen oxide conversion efficiency of the corresponding first nitrogen oxide treatment device A2 can be queried through the MAP table. In addition, the air velocity can be determined by the exhaust gas mass flow rate, the exhaust gas density and the volume of the first nitrogen oxide treatment device A2. Specifically, air velocity = exhaust gas mass flow rate / (exhaust gas density*volume of the first nitrogen oxide treatment device A2).

[0061] S224: Calculating a pre-stage urea injection amount of the pre-stage urea mixer according to the exhaust gas mass flow rate, the nitrogen oxide concentration before the pre-stage urea mixer, and the nitrogen oxide conversion efficiency of the first nitrogen oxide treatment device.

[0062] While determining the NOx conversion efficiency of the first NOx treatment device A2, the exhaust gas mass flow rate and the NOx concentration before the pre-stage urea mixer A1 are obtained. The specific NOx concentration before the pre-stage urea mixer A1 can be obtained by the first NOx sensor N1 installed before the pre-stage urea mixer A1. Based on the exhaust gas mass flow rate and the NOx concentration before the pre-stage urea mixer A1, the mass flow rate of nitrogen oxides (NOx) entering the NOx treatment device A2 is calculated. The molar mass of NOx is 46 g / mol. The specific NOx mass flow rate = exhaust gas mass flow rate before the pre-stage urea mixer A1 * NOx concentration before the pre-stage urea mixer A1 * 46 / 29 * (1e-6). The conversion amount of nitrogen oxides in front of the nitrogen oxide treatment device A2 can be calculated by multiplying the mass flow rate of nitrogen oxides in front of the nitrogen oxide treatment device A2 by the nitrogen oxide conversion efficiency of the first nitrogen oxide treatment device A2. The mass flow rate of ammonia is calculated based on the conversion amount of nitrogen oxides in front of the nitrogen oxide treatment device A2. The specific calculation formula is: mass flow rate of ammonia = conversion amount of nitrogen oxides in front of the nitrogen oxide treatment device A2 * 17 / 46. Finally, the pre-stage urea injection amount of the pre-stage urea mixer A1 is calculated based on the mass flow rate of ammonia. The molar mass of urea is 60 g / mol, 1 mol of urea contains 2 mol of ammonia, and the molar mass of ammonia is 17 g / mol. The pre-stage urea injection amount = mass flow rate of ammonia * 60 / (2 * 17 * concentration of urea solution).

[0063] In one embodiment of the present application, Figure 5 As shown, in S30, the amount of urea crystallization is controlled in stages according to the amount of urea crystallization in the preceding urea mixer. The specific steps may include: S31: When the amount of urea crystals in the front-stage urea mixer is greater than or equal to a first preset threshold, controlling the front-stage urea injection amount to decrease and controlling the rear-stage urea injection amount to increase.

[0064] A first preset threshold is set in advance, for example, the first preset threshold is 10 g. After the urea crystal amount of the front-stage urea mixer A1 is calculated, the urea crystal amount of the front-stage urea mixer A1 is compared with the first preset threshold. When the urea crystal amount of the front-stage urea mixer is greater than or equal to the first preset threshold, the front-stage urea injection amount is controlled to decrease, and the rear-stage urea injection amount is controlled to increase.

[0065] Specifically, the front-stage urea injection amount may be controlled according to the above steps S221 to S224 .

[0066] In this embodiment, the amount of urea crystals is controlled by setting a first preset threshold value of the amount of urea crystals in the front-stage urea mixer A1. This allows the injection amount of urea to be precisely controlled to avoid crystallization caused by excessive injection. This not only improves the utilization efficiency of urea, but also ensures the efficient operation of the exhaust gas treatment system. In addition, reducing the amount of urea crystals in the front-stage urea mixer A1 can ensure the cleanliness of the catalyst surface of the first nitrogen oxide treatment device A2, thereby improving the nitrogen oxide conversion efficiency of the first nitrogen oxide treatment device A2 and ensuring that the nitrogen oxides emitted from the exhaust gas of the first nitrogen oxide treatment device A2 meet the standards.

[0067] In one embodiment of the present application, the steps of obtaining the subsequent urea injection amount of the subsequent urea mixer may include: S231: Acquire the temperature after the particle processing device.

[0068] Specifically, the temperature after the particle processing device A3 can be obtained by using a third temperature sensor T3 disposed after the particle processing device A3.

[0069] S232: Determine the nitrogen oxide conversion efficiency of the second nitrogen oxide treatment device according to the mapping relationship between the temperature and the space velocity after the particulate treatment device.

[0070] Similarly, after determining the temperature T3 and air velocity after particulate treatment device A3, the NOx conversion efficiency of second NOx treatment device A5 can be calculated using the NOx conversion efficiency MAP table. Furthermore, air velocity can be determined based on the exhaust gas mass flow rate, exhaust gas density, and the volume of second NOx treatment device A5. Specifically, air velocity = exhaust gas mass flow rate / (exhaust gas density * volume of second NOx treatment device A5).

[0071] S233: Calculate the proportion of nitrogen dioxide in nitrogen oxides, and correct the nitrogen oxide conversion efficiency of the second nitrogen oxide treatment device according to the proportion of nitrogen dioxide in nitrogen oxides.

[0072] Among them, the proportion of nitrogen dioxide in nitrogen oxides = nitrogen dioxide / nitrogen oxides.

[0073] S234: Calculating a subsequent urea injection amount of the subsequent urea mixer according to the exhaust gas mass flow rate, the nitrogen oxide concentration before the particulate treatment device, and the nitrogen oxide conversion efficiency of the second nitrogen oxide treatment device.

[0074] While determining the NOx conversion efficiency of the second NOx treatment device A5, the exhaust gas mass flow rate before the second NOx treatment device A5 and the NOx concentration before the particulate treatment device A3 are obtained. Specifically, the second NOx concentration of the exhaust gas before the particulate treatment device A3 can be detected by a second NOx sensor N2 disposed between the first NOx treatment device A2 and the particulate treatment device A3. Based on the exhaust gas mass flow rate before the second NOx treatment device A5, the second NOx concentration before the particulate treatment device A3, and the NOx conversion efficiency of the second NOx treatment device A5, the subsequent urea injection amount of the subsequent urea mixer A4 can be calculated. The specific calculation process is similar to the calculation process for the preceding urea injection amount of the preceding urea mixer and will not be further described here.

[0075] It is understandable that the subsequent urea injection amount can be controlled according to the above steps S231 to S234.

[0076] In one embodiment of the present application, Figure 6 As shown, when the urea crystal amount of the front-stage urea mixer is greater than or equal to the first preset threshold, the urea injection amount of the front-stage is controlled to decrease, and the urea injection amount of the rear-stage is controlled to increase, that is, after S31, the following steps may be further included: S40: When the crystallization amount is less than or equal to the second preset threshold, exit the graded control of the crystallization amount.

[0077] After implementing the steps of controlling the front-stage urea injection amount to decrease and controlling the rear-stage urea injection amount to increase, the amount of urea crystals in the front-stage urea mixer A1 may show an increasing trend or a decreasing trend. If the amount of urea crystals in the front-stage urea mixer A1 shows a decreasing trend, the amount of urea crystals in the front-stage urea mixer A1 is continuously monitored and compared with a second preset threshold value. When the amount of crystals is less than or equal to the second preset threshold value, the amount of urea crystals in the front-stage urea mixer A1 has met the preset requirement, resulting in a high efficiency of the SCR catalytic conversion in the first nitrogen oxide treatment device A2, and the nitrogen oxides emitted from the exhaust gas of the first nitrogen oxide treatment device A2 meeting the standard. Ultimately, the nitrogen oxides emitted from the exhaust gas of the second nitrogen oxide treatment device A5 in the after-treatment system also meet the standard. Therefore, it is temporarily unnecessary to control the amount of urea crystals in the front-stage urea mixer A1. The first preset threshold value is greater than the second preset threshold value, and the second preset threshold value is also preset. For example, the second preset threshold value is 3g.

[0078] In this embodiment, by setting a second preset threshold value of the crystallization amount, a timing for exiting the control of the urea crystallization amount of the front-stage urea mixer A1 is given, that is, the front-stage urea injection amount and the rear-stage urea injection amount are no longer controlled, thereby avoiding unnecessary intervention of the post-treatment system on the urea crystallization amount during normal operation.

[0079] In one embodiment of the present application, Figure 7 As shown, when the urea crystal amount of the front-stage urea mixer is greater than or equal to the first preset threshold, the urea injection amount of the front-stage is controlled to decrease, and the urea injection amount of the rear-stage is controlled to increase, that is, after S31, the following steps may be further included: S32: When the amount of urea crystals in the front-stage urea mixer is greater than or equal to a third preset threshold, the engine thermal management system is started to increase the temperature before the front-stage urea mixer.

[0080] After controlling the front-stage urea injection amount to decrease and the rear-stage urea injection amount to increase, if the urea crystal amount in the front-stage urea mixer shows an increasing trend, the urea crystal amount in the front-stage urea mixer A1 is also monitored and compared with a third preset threshold. If the urea crystal amount in the front-stage urea mixer A1 is greater than or equal to the third preset threshold, the urea crystal amount is excessive and continuing to control the front-stage urea injection amount to decrease and the rear-stage urea injection amount to increase is ineffective in reducing the urea crystal amount. In this case, the engine thermal management system is activated, such as by retarding the lead angle and reducing the intake air volume, to worsen combustion and increase the exhaust gas temperature after the turbine, that is, to increase the exhaust gas temperature before the front-stage urea mixer A1. The third preset threshold is greater than the first preset threshold and is also pre-set, for example, 20g.

[0081] In this embodiment, by setting two preset thresholds of crystallization amount, a third preset threshold and a first preset threshold (the third preset threshold is greater than the first preset threshold), the amount of urea crystallization in the post-treatment system is reduced in stages. When the amount of urea crystallization in the front-stage urea mixer A1 is greater than or equal to the first preset threshold, only the front-stage urea injection amount and the rear-stage urea injection amount are controlled to reduce the amount of urea crystallization. When the amount of urea crystallization in the front-stage urea mixer A1 is greater than or equal to the third preset threshold, the engine thermal management system is activated to increase the temperature before the front-stage urea mixer to further reduce the amount of urea crystallization. That is, when the amount of urea crystallization in the front-stage urea mixer A1 is greater than or equal to the third preset threshold, the engine thermal management system is activated to increase the temperature before the front-stage urea mixer to further reduce the amount of urea crystallization. Different control methods are used for the amount of crystallization. This dual-threshold strategy allows for more precise control of the amount of urea crystallization, improving the reliability of the post-treatment system and the efficiency of removing urea crystals. It ensures that the amount of urea crystals in the front-stage urea mixer A1 is always within a preset range, thereby improving the efficiency of the SCR catalytic conversion in the first NOx treatment device A2, thereby reducing the NOx emissions of the first NOx treatment device A2, reducing the risk of crystallization in the rear-stage urea mixer A4, and ultimately improving the efficiency of the SCR catalytic conversion in the second NOx treatment device A5, ensuring that the final NOx and particulate matter emissions meet the standards.

[0082] In one embodiment of the present application, Figure 8 As shown, when the amount of urea crystals in the front-stage urea mixer is greater than or equal to the third preset threshold, the engine thermal management system is started to increase the temperature before the front-stage urea mixer, that is, after S32, the following steps may be further included: S50: When the crystallization amount is less than or equal to a fourth preset threshold, exiting the graded control of the crystallization amount.

[0083] When the amount of urea crystallization of the front-stage urea mixer presents a decreasing trend after the engine thermal management system is started to improve the temperature before the front-stage urea mixer, the amount of urea crystallization of the front-stage urea mixer A1 is also monitored and compared with the fourth preset threshold value, and when the amount of urea crystallization is less than or equal to the fourth preset threshold value, at this time, the amount of urea crystallization of the front-stage urea mixer A1 has met the preset requirement, the efficiency of the SCR catalytic conversion in the first nitrogen oxide treatment device A2 is relatively high, the nitrogen oxide emitted by the tail gas of the first nitrogen oxide treatment device A2 meets the standard, and finally the nitrogen oxide emitted by the tail gas of the second nitrogen oxide treatment device A5 in the aftertreatment system also meets the standard, therefore, it is not necessary to control the amount of urea crystallization of the front-stage urea mixer A1 temporarily, that is, the step of controlling the amount of urea crystallization is exited, wherein the third preset threshold value is greater than the fourth preset threshold value, and the fourth preset threshold value is also preset, for example, the fourth preset threshold value is 3g. The fourth preset threshold value and the second preset threshold value are both crystallization threshold values for exiting the step of controlling the amount of urea crystallization, but there is no explicit size relationship, and the fourth preset threshold value can be equal to or not equal to the second preset threshold value.

[0084] By setting the fourth preset threshold value of the amount of urea crystallization, the timing of exiting the control of the amount of urea crystallization of the front-stage urea mixer A1 is given, that is, the front-stage urea injection amount, the rear-stage urea injection amount and the engine thermal management are not controlled, unnecessary intervention of the aftertreatment system on the amount of urea crystallization during normal operation can be avoided, unnecessary heating operation can be reduced, energy consumption can be reduced, and the overall energy efficiency of the aftertreatment system can be improved.

[0085] Exemplary device As a third aspect of the present application, the present application also provides an aftertreatment system urea crystallization control device, Figure 9 As shown in the working block diagram of the aftertreatment system urea crystallization control device provided by an embodiment of the present application, Figure 9 As shown, the fault self-recovery controller 900 comprises: The data acquisition module 901 is configured to acquire the temperature before the first nitrogen oxide treatment device, the exhaust gas mass flow and the front-stage urea injection amount of the front-stage urea mixer.

[0086] Specifically, the data acquisition module 901 is configured to perform the step of acquiring the temperature before the first nitrogen oxide treatment device, the exhaust gas mass flow and the front-stage urea injection amount of the front-stage urea mixer in S10 of the aftertreatment system urea crystallization control method.

[0087] The calculation module 902 is configured to calculate the amount of urea crystallization of the front-stage urea mixer according to the temperature before the first nitrogen oxide treatment device, the exhaust gas mass flow and the front-stage urea injection amount of the front-stage urea mixer.

[0088] Specifically, the calculation module 902 is used to execute the step of calculating the urea crystallization amount of the front-stage urea mixer according to the temperature and exhaust gas mass flow rate before the first nitrogen oxide treatment device and the front-stage urea injection amount of the front-stage urea mixer in S20 in the above-mentioned urea crystallization control method of the post-treatment system.

[0089] The control module 903 is used to perform graded control on the amount of urea crystals according to the amount of urea crystals in the preceding urea mixer.

[0090] Specifically, the control module 903 is used to execute the step of performing graded control on the amount of urea crystals according to the amount of urea crystals in the preceding urea mixer in S30 in the above-mentioned method for controlling urea crystals in the post-treatment system.

[0091] The urea crystallization control device for the post-treatment system provided in the present application obtains the temperature and exhaust gas mass flow rate before the first nitrogen oxide treatment device A2, and the pre-stage urea injection amount of the pre-stage urea mixer A1. Based on the temperature and exhaust gas mass flow rate before the first nitrogen oxide treatment device A2 and the pre-stage urea injection amount of the pre-stage urea mixer A1, the urea crystallization amount of the pre-stage urea mixer is calculated. Based on the urea crystallization amount of the pre-stage urea mixer A1, the crystallization amount is controlled in stages, so that the urea crystallization amount of the pre-stage urea mixer A1 is controlled within a preset range, thereby improving the efficiency of SCR catalytic conversion, thereby reducing the emissions of nitrogen oxides and particulate matter.

[0092] In addition, the post-treatment system urea crystallization control device provided in this embodiment is based on the same application concept as the post-treatment system urea crystallization control method provided in the above-mentioned embodiments of this application. It can implement the post-treatment system urea crystallization control method provided in any of the above-mentioned embodiments of this application and has the corresponding functional units and beneficial effects of executing the post-treatment system urea crystallization control method. For technical details not fully described in this embodiment, please refer to the specific processing content of the post-treatment system urea crystallization control method provided in the above-mentioned embodiments of this application, and will not be repeated here.

[0093] Example Vehicle As a third aspect of the present application, the present application also provides a vehicle, comprising the after-treatment system described in the first aspect above.

[0094] The methods of this application can be implemented in whole or in part using software, hardware, firmware, or any combination thereof. When implemented using software, they can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer programs or instructions that, when loaded and executed on a computer, fully or partially execute the processes or functions of this application. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user device, a core network device, an OAM, or other programmable device.

[0095] The computer program product may be written in any combination of one or more programming languages ​​to implement the program code for performing the operations of the embodiments of the present application, including object-oriented programming languages ​​such as Java, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0096] A computer program or instruction can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, a computer program or instruction can be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. A computer-readable storage medium can be any available medium that can be accessed by a computer, or a data storage device such as a server or data center that integrates one or more available media. Available media can be magnetic media, such as floppy disks, hard disks, or magnetic tapes; optical media, such as digital video disks; or semiconductor media, such as solid-state drives. The computer-readable storage medium can be volatile or non-volatile, or can include both volatile and non-volatile types of storage media.

[0097] In addition, an embodiment of the present application may also be a storage medium having a computer program stored thereon, and the computer program is used by a processor to execute the steps of a urea crystallization control method for a post-treatment system described in any of the above embodiments of this specification: For the sake of simplicity, the aforementioned method embodiments are described as a series of action combinations. However, those skilled in the art should be aware that this application is not limited by the order of the actions described, because according to this application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in this specification are all preferred embodiments, and the actions and modules involved are not necessarily required by this application.

[0098] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similarities between the various embodiments can be referred to in conjunction with each other. For device embodiments, since they are generally similar to method embodiments, their description is relatively simple, and for relevant details, reference can be made to the description of the method embodiments.

[0099] The steps in the methods of the various embodiments of the present application can be adjusted in order, combined, or deleted according to actual needs, and the technical features recorded in the various embodiments can be replaced or combined. The devices in the various embodiments of the present application can be combined, divided, or deleted according to actual needs.

[0100] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the components and steps of each example according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0101] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, software executed by a processor, or a combination of the two. The software may be stored in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0102] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0103] The above description of the disclosed embodiments will enable those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A urea crystallization control method for a post-processing system, characterized in that: The control method is applicable to a post-treatment system, which includes: a front-stage urea mixer, which injects front-stage urea and mixes the injected urea with exhaust gas; a first nitrogen oxide treatment device, which uses a reducing catalyst and an oxidizing catalyst to reduce nitrogen oxides and oxidize ammonia using the front-stage urea injected by the front-stage urea mixer; a particulate treatment device, which uses an oxidizing catalyst to capture particulates and nitrogen oxides; a rear-stage urea mixer, which mixes rear-stage urea injected after the particulate treatment device with exhaust gas; and a second nitrogen oxide treatment device, which uses a reducing catalyst and an oxidizing catalyst to reduce nitrogen oxides and oxidize ammonia using the urea injected after the particulate treatment device. Wherein, the control method includes: Acquiring the temperature and exhaust gas mass flow rate before the first nitrogen oxide treatment device, and the pre-stage urea injection amount of the pre-stage urea mixer; calculating the amount of urea crystals in the front-stage urea mixer according to the temperature before the first nitrogen oxide treatment device, the exhaust gas mass flow rate, and the front-stage urea injection amount of the front-stage urea mixer; The amount of urea crystals is controlled in stages according to the amount of urea crystals in the preceding urea mixer.

2. The urea crystallization control method according to claim 1, characterized in that: Obtaining the temperature before the first nitrogen oxide treatment device includes: Acquiring the temperature and exhaust gas mass flow rate before the front-stage urea mixer, and the front-stage urea injection amount of the front-stage urea mixer; The temperature before the first nitrogen oxide treatment device is calculated according to the temperature before the front-stage urea mixer, the exhaust gas mass flow rate, and the front-stage urea injection amount of the front-stage urea mixer.

3. The urea crystallization control method according to claim 1, characterized in that: According to the urea crystallization amount of the previous urea mixer, the crystallization amount is controlled in stages, including: When the amount of urea crystals in the front-stage urea mixer is greater than or equal to a first preset threshold, the front-stage urea injection amount is controlled to decrease, and the rear-stage urea injection amount is controlled to increase.

4. The urea crystallization control method according to claim 3, characterized in that: The control method further includes: When the crystallization amount is less than or equal to a second preset threshold, the graded control of the crystallization amount is exited, wherein the first preset threshold is greater than the second preset threshold.

5. The urea crystallization control method according to claim 3, characterized in that: According to the amount of urea crystals in the front-stage urea mixer, the amount of crystals is controlled in stages, including: When the amount of urea crystals in the front-stage urea mixer is greater than or equal to a third preset threshold, the engine thermal management system is started to increase the temperature before the front-stage urea mixer, wherein the third preset threshold is greater than the first preset threshold.

6. The urea crystallization control method according to claim 5, characterized in that: The control method further includes: When the crystallization amount is less than or equal to a fourth preset threshold, the graded control of the crystallization amount is exited, wherein the third preset threshold is greater than the fourth preset threshold.

7. The urea crystallization control method according to claim 1, characterized in that: The obtaining of the front-stage urea injection amount of the front-stage urea mixer includes: obtaining a temperature after the first nitrogen oxide treatment device; calculating an average temperature of the first nitrogen oxide treatment device according to a temperature before the first nitrogen oxide treatment device and a temperature after the first nitrogen oxide treatment device; determining a nitrogen oxide conversion efficiency based on a mapping relationship between an average temperature and a space velocity of the first nitrogen oxide treatment device; The pre-stage urea injection amount of the pre-stage urea mixer is calculated according to the exhaust gas mass flow, the nitrogen oxide concentration before the pre-stage urea mixer, and the nitrogen oxide conversion efficiency.

8. A urea crystallization control device for a post-processing system, characterized in that: include: A data acquisition module, used to obtain the temperature and exhaust gas mass flow rate before the first nitrogen oxide treatment device, and the pre-stage urea injection amount of the pre-stage urea mixer; a calculation module, configured to calculate the amount of urea crystals in the front-stage urea mixer according to the temperature before the first nitrogen oxide treatment device, the exhaust gas mass flow rate, and the front-stage urea injection amount of the front-stage urea mixer; The control module is used to perform graded control on the amount of urea crystals according to the amount of urea crystals in the preceding urea mixer.

9. A post-processing system, characterized in that: include: a pre-stage urea mixer, which injects pre-stage urea and mixes the injected urea with the exhaust gas; The first nitrogen oxide treatment device uses a reducing catalyst and an oxidizing catalyst to reduce nitrogen oxides and oxidize ammonia using the pre-stage urea injected from the pre-stage urea mixer; A particulate matter processor uses an oxidizing catalyst to capture particulates and nitrogen oxides; A post-stage urea mixer, which mixes the post-stage urea injected after the particle treatment device with the exhaust gas; A second nitrogen oxide treatment device employs a reducing catalyst and an oxidizing catalyst, utilizing urea injected after the particulate treatment device to reduce nitrogen oxides and oxidize ammonia; The controller is configured to obtain a temperature before a first nitrogen oxide treatment device, an exhaust gas mass flow rate, and a pre-stage urea injection amount of a pre-stage urea mixer; calculate a urea crystallization amount of the pre-stage urea mixer based on the temperature before the first nitrogen oxide treatment device, the exhaust gas mass flow rate, and the pre-stage urea injection amount of the pre-stage urea mixer; and perform graded control on the crystallization amount based on the urea crystallization amount of the pre-stage urea mixer.

10. A vehicle, characterized in that: include: The aftertreatment system of claim 9.

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