Parallel post-processing system, control method, device and storage medium

Abstract

This application proposes a parallel aftertreatment system, control method, device, and storage medium. The parallel aftertreatment system includes a first branch and a second branch connected in parallel. The input ends of the first and second branches are connected to the engine exhaust pipe. A first temperature measuring module is disposed between the input end and the engine exhaust pipe. A first urea injection mixing module and a first nitrogen oxide purification module are sequentially disposed along the exhaust flow direction in the first branch. The second branch includes a pollutant pre-purification module. A particulate matter capture module and a second nitrogen oxide purification module are sequentially connected in series at the output ends of the first and second branches. A second temperature measuring module, a nitrogen oxide concentration sensor, and a second urea injection mixing module are disposed between the particulate matter capture module and the second nitrogen oxide purification module. The embodiments of this application can greatly improve the purification efficiency of exhaust gas.

Description

Technical Field

[0001] This application relates to the field of exhaust gas aftertreatment technology, specifically to a parallel aftertreatment system, control method, device and storage medium. Background Technology

[0002] Currently, diesel engines generally adopt a series aftertreatment system consisting of "DOC (Diesel Oxidation Catalyst) + DPF (Diesel Particulate Filter) + SCR (Selective Catalytic Reduction) & ASC (Ammonia Slip Catalyst)".

[0003] The existing series structure has the following technical defects: 1. The SCR device is located at the rear end. During engine cold start, due to the heat capacity of DOC and DPF carriers, the process of SCR reaching the urea injection temperature (about 185°C) is slow. This means that the NOx emitted by the original engine cannot be treated during this period, resulting in high NOx in the cold WHTC cycle exhaust. 2. Since urea injection contributes to PN, and SCR is placed after DPF, some of the PN generated by urea injection cannot be effectively captured and is included in the tail discharge.

[0004] 3. Since SCR catalyst side reactions produce N2O, primarily from the decomposition of ammonium nitrate (NH4NO3) at low temperatures and the oxidation of ammonia at high temperatures (ammonium nitrate is generated from NH3 + NO2), placing SCR after DOC + DPF (where NO is oxidized to NO2) promotes the formation of both ammonium nitrate and N2O. Furthermore, urea is often over-sprayed, leading to an increase in N2O formation from the ammonia oxidation side reaction at high temperatures. Therefore, the DOC + DPF pre-positioning and excessive urea injection both exacerbate the formation of N2O, this "hidden pollutant."

[0005] Therefore, the existing aftertreatment system series structure has the problem of high system cold-state NOx, system N2O emissions and PN emissions. Summary of the Invention

[0006] In view of this, this application proposes a parallel after-treatment system, control method, device and storage medium to solve the problems of high system cold-state NOx, system N2O and PN emissions in the existing series structure of after-treatment systems.

[0007] The first aspect of this application provides a parallel after-treatment system, which includes a first branch and a second branch arranged in parallel. The input ends of the first branch and the second branch are used to connect to the engine exhaust pipe. A first temperature measuring module is provided between the input end and the engine exhaust pipe. The first branch is provided with a first urea injection mixing module and a first nitrogen oxide purification module in sequence along the exhaust flow direction; the second branch includes a pollutant pre-purification module; the output ends of the first branch and the second branch are connected in series with a particulate matter collection module and a second nitrogen oxide purification module. A second temperature measuring module, a nitrogen oxide concentration sensor, and a second urea injection mixing module are provided between the particulate matter collection module and the second nitrogen oxide purification module.

[0008] In this embodiment, the pre-SCR (i.e., the first nitrogen oxide purification module in the first branch) is directly connected to the engine exhaust pipe, which can shorten the time for the pre-SCR to reach the urea injection temperature (about 185°C), thereby increasing the heating rate of the SCR and greatly shortening the injection time, which helps to improve the NOx conversion efficiency. This application embodiment uses a pre-stage SCR (i.e., the first nitrogen oxide purification module in the first branch) to reduce the pressure of the subsequent SCR and improve the system emission robustness; the PN generated by the urea injection of the pre-stage SCR can be captured by the DDPF (i.e., particulate matter capture module), reducing the system PN emission; the NO2 concentration at the inlet of the pre-stage SCR is low (NO2 accounts for a very small proportion of the original machine emission), reducing the formation of N2O at low temperatures; the amount of urea injected by the subsequent SCR is reduced, reducing the formation of N2O at high temperatures.

[0009] Therefore, the embodiments of this application can reduce system cold-state NOx, system N2O emissions, and PN emissions, thereby improving system emission robustness. Furthermore, this approach does not increase the length of the aftertreatment system, facilitating vehicle layout.

[0010] This application embodiment constructs a dual-path system (i.e., the first and second branches mentioned above). Specifically, based on the traditional diesel engine aftertreatment system DOC+DPF+SCR&ASC, a pre-stage SCR&ASC is added in parallel with the DOC. This allows the DOC in the second branch to oxidize the NO in the exhaust gas of that branch to NO2, thereby increasing the NO2 ratio before DDPF. This satisfies the passive regeneration consumption of DDPF while ensuring that the SCR has enough NO2 to activate a rapid response.

[0011] In this embodiment, the particulate matter capture module includes a composite catalytic converter, which refers to coating the surface of the intake channel of the diesel particulate filter with a diesel oxidation catalytic coating to form a series structure of a front-end oxidation zone and a rear-end capture zone.

[0012] In this embodiment, the traditional DPF is replaced with DDPF (DOC on DPF). A DOC catalyst is coated at the front end of the DPF, allowing HC leaked from both branches to be treated secondary by the DDPF. The DOC in the second branch only needs to treat the HC in its own branch, significantly reducing its load. Furthermore, even if the oxidation efficiency of the DOC in the second branch decreases due to carbon buildup or aging, the DDPF can act as a safety net to handle the remaining HC.

[0013] In this embodiment of the application, for any one of the first nitrogen oxide purification module and the second nitrogen oxide purification module, the nitrogen oxide purification module includes a selective catalytic reduction device and an ammonia purifier connected in series. The selective catalytic reduction device is used to purify nitrogen oxides in exhaust gas; The ammonia purifier is used to purify the ammonia generated by the selective catalytic reduction unit during the purification of nitrogen oxides.

[0014] In this embodiment of the application, for any one of the first urea injection mixing module and the second urea injection mixing module, the urea injection mixing module includes a urea injection device and a mixer.

[0015] In this embodiment of the application, the engine includes a diesel engine, and the pollutant pre-purification module includes a diesel oxidation catalyst.

[0016] An embodiment of the second aspect of this application provides a control method for a parallel post-processing system, the control method being applied to the parallel post-processing system described in the first aspect; the control method includes: After the engine starts, the first temperature of the first temperature measuring module, the second temperature of the second temperature measuring module, and the first nitrogen oxide concentration of the nitrogen oxide concentration sensor are acquired, and the second nitrogen oxide concentration of the engine exhaust pipe is calculated based on the engine operating parameters; the engine operating parameters include at least one of the following: engine speed, engine torque, fuel injection quantity, and fuel injection timing; Compare the magnitudes of the first temperature, the second temperature, and the urea spraying temperature; If the first temperature is greater than the urea injection temperature and the second temperature is less than the urea injection temperature, the first urea injection quantity is calculated based on the second nitrogen oxide concentration and the exhaust flow rate of the engine exhaust pipe, and the first urea injection device is controlled to inject according to the first urea injection quantity, while the second urea injection device is kept closed.

[0017] In this embodiment of the application, the method further includes: If the first temperature is greater than the urea injection temperature and the second temperature is greater than the urea injection temperature, then the first urea injection quantity is calculated based on the second nitrogen oxide concentration and the exhaust flow rate of the engine exhaust pipe, and the second urea injection quantity is calculated based on the first nitrogen oxide concentration and the exhaust flow rate of the engine exhaust pipe. The first urea injection device is controlled to inject urea according to the first urea injection amount, and the second urea injection device is controlled to inject urea according to the second urea injection amount.

[0018] An embodiment of the third aspect of this application provides a control device for a parallel post-processing system, comprising: The temperature measurement module is used to acquire the first temperature of the first temperature measurement module, the second temperature of the second temperature measurement module, and the first nitrogen oxide concentration of the nitrogen oxide concentration sensor after the engine is started, and to calculate the second nitrogen oxide concentration of the engine exhaust pipe based on the engine operating parameters; the engine operating parameters include at least one of the following: engine speed, engine torque, cyclic fuel injection quantity, and fuel injection timing; A temperature comparison module is used to compare the magnitudes of the first temperature, the second temperature, and the urea spraying temperature. The urea injection module is used to calculate the first urea injection quantity based on the second nitrogen oxide concentration and the exhaust flow rate of the engine exhaust pipe if the first temperature is greater than the urea injection temperature and the second temperature is less than the urea injection temperature, and control the first urea injection device to inject according to the first urea injection quantity, while keeping the second urea injection device closed.

[0019] An embodiment of the fourth aspect of this application provides a computer device including a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to perform the control method of the parallel post-processing system described in the second aspect above.

[0020] An embodiment of the fifth aspect of this application provides a computer-readable storage medium storing computer instructions for causing a computer to execute the control method of the parallel post-processing system described in the second aspect above.

[0021] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0022] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This invention provides a schematic diagram of the structure of a parallel post-processing system according to an embodiment of the present application. Figure 2 A schematic diagram of another parallel post-processing system provided in one embodiment of this application is shown; Figure 3 A schematic flowchart of a control method for a parallel post-processing system according to an embodiment of this application is shown. Figure 4 A flowchart illustrating a control method for another parallel post-processing system provided in an embodiment of this application is shown. Figure 5 This invention provides a schematic diagram of the structure of a control device for a parallel post-processing system according to an embodiment of the present application. Figure 6 This illustration shows a schematic diagram of the structure of a computer device according to an embodiment of this application; Figure 7 A schematic diagram of a storage medium provided in one embodiment of this application is shown. Detailed Implementation

[0023] Exemplary embodiments of this application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0024] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application shall have the ordinary meaning as understood by one of ordinary skill in the art to which this application pertains.

[0025] The following describes the relevant terminology and technical scenarios involved in the embodiments of this application.

[0026] DOC (Diesel Oxidation Catalyst): Through catalytic oxidation reactions, it converts carbon monoxide (CO), hydrocarbons (HC), and some particulate matter (PM) in diesel engine exhaust into carbon dioxide (CO2) and water (H2O), and oxidizes NO into NO2.

[0027] DPF (Diesel Particulate Filter): Used to capture and remove particulate matter (PM) (including soot, ash, soluble organic matter SOF, etc.) from diesel exhaust.

[0028] SCR (Selective Catalytic Reduction): A device that converts nitrogen oxides (NOx) in exhaust gas into harmless nitrogen (N2) and water (H2O) by injecting urea solution (AdBlue) into the exhaust gas.

[0029] SCR fast reaction: The reaction of NH3 with NO2 to produce N2 and H2O has a faster reaction rate than other SCR reactions such as the reaction of NH3 with NO and the reaction of NH3 with NO and NO2.

[0030] ASC (Ammonia Slip Catalyst): Used to treat leaked ammonia by oxidizing it into N2.

[0031] DDPF (DOC on DPF): A composite catalyst of DOC and DPF, in which DOC is coated on the front end of the DPF, enabling it to oxidize HC and achieve active regeneration by raising the temperature.

[0032] Active regeneration: When the carbon load inside the particulate filter reaches the limit, HC is injected into the exhaust gas. The precious metal oxide coating oxidizes the HC and releases heat, thereby raising the temperature of the particulate filter and oxidizing the carbon soot into CO2.

[0033] Passive regeneration: using a precious metal oxide coating to oxidize NO in the exhaust gas into NO2, thereby achieving carbon removal in the particulate filter at low temperatures (2C+2NO2→2CO2+N2).

[0034] MFC (Mixed Functional Catalyst): Based on SCR catalyst, noble metals such as Pd are added, so that it can not only reduce NOx, but also oxidize HC and desulfurize, avoiding the impact of HC on NOx conversion efficiency when SCR is placed before DOC.

[0035] NOx: Nitrogen oxides, combustion products of engines.

[0036] N2O: Nitrous oxide, commonly known as laughing gas, is a by-product of the NOx reduction process by SCR catalyst.

[0037] PN (Particulate Number): The number concentration of suspended particulate matter in diesel engine exhaust or air, typically used to measure the pollution level of ultrafine particles (such as nanoparticles).

[0038] Urea: Used in diesel vehicle SCR systems, it is injected into the exhaust gas before the SCR system to reduce nitrogen oxide (NOx) emissions through a chemical reaction.

[0039] WHTC (World Harmonized Transient Cycle): A standard chemical cycle used to test exhaust emissions from diesel vehicles and non-road mobile machinery.

[0040] Currently, the "DOC+DPF+SCR&ASC" series aftertreatment system for diesel engines still has the following technical defects: 1. With the SCR device placed at the rear end, during engine cold starts, due to the heat capacity of the DOC and DPF carriers, the SCR reaches the urea injection temperature (approximately 185°C) slowly, resulting in the NOx emitted by the original engine being unable to be treated during this period, leading to high NOx levels in the cold-state WHTC cycle exhaust; 2. Since urea injection contributes to particulate matter (PN), and the SCR is placed after the DPF, some of the PN generated by urea injection cannot be effectively captured and is included in the exhaust; 3. The SCR catalyst side reaction produces N2O, mainly from the decomposition of ammonium nitrate (NH4NO3) at low temperatures and the oxidation of ammonia at high temperatures. Ammonium nitrate is generated from NH3 + NO2. Placing the SCR after DOC+DPF (NO is oxidized to NO2) will promote the formation of ammonium nitrate and N2O; in addition, urea is often over-injected, leading to an increase in N2O generated by the ammonia oxidation side reaction at high temperatures.

[0041] To address the aforementioned technical deficiencies, this application provides a parallel after-treatment system and a control method for the parallel after-treatment system, which can significantly improve the pollutant purification rate of the after-treatment system.

[0042] This application provides a parallel post-processing system in its embodiments. Figure 1 This is a schematic diagram of the structure of a parallel post-processing system according to an embodiment of this application, as shown below. Figure 1 As shown, the parallel aftertreatment system includes a first branch and a second branch arranged in parallel. The input ends of the first branch and the second branch are used to connect to the engine exhaust pipe. A first temperature measuring module 101 is arranged between the input end and the engine exhaust pipe. A first urea injection mixing module 102 and a first nitrogen oxide purification module 103 are arranged sequentially along the exhaust flow direction of the first branch. The second branch includes a pollutant pre-purification module 104. A particulate matter collection module 105 and a second nitrogen oxide purification module 106 are connected in series at the output ends of the first branch and the second branch. A second temperature measuring module 107, a nitrogen oxide concentration sensor 108, and a second urea injection mixing module 109 are arranged between the particulate matter collection module 105 and the second nitrogen oxide purification module 106.

[0043] The parallel post-processing system in this application embodiment can achieve the following technical effects: 1. The pre-stage SCR (i.e., the first nitrogen oxide purification module 103 in the first branch above) removes most of the NOx (usually 50-70%), and the post-stage SCR (i.e., the second nitrogen oxide purification module 106 above) only needs to clean up the tail end, which can greatly reduce the pressure on the post-stage SCR and improve the emission robustness of the aftertreatment system.

[0044] 2. In traditional aftertreatment systems, since the SCR is located after the output of the DPF, the PN generated by the SCR urea injection is directly discharged into the atmosphere. However, in the present application, the PN generated by the pre-stage SCR urea injection is captured by the DDPF, which can reduce the PN emission rate to a certain extent.

[0045] 3. The input end of the pre-stage SCR is directly connected to the engine exhaust pipe and not to the output end of the DOC. Therefore, the NO2 concentration at the inlet end of the pre-stage SCR is extremely low, and it hardly generates NH4NO3 with the NH3 injected by urea. As a result, it is impossible to generate N2O through "NH4NO3 decomposition under temperature fluctuation conditions", thus greatly reducing the cold N2O emission rate.

[0046] 4. Since the upstream SCR has already treated most of the NOx, the urea injection rate of the downstream SCR will be reduced (e.g., 30-50%). With the reduction in the urea injection rate of the downstream SCR, the ammonia oxidation side reaction caused by over-injection of urea will be weakened accordingly, thereby inhibiting the generation of high-temperature N2O and achieving the goal of reducing the high-temperature N2O emission rate.

[0047] In this embodiment, cold N2O emissions are primarily based on the ammonium nitrate decomposition pathway, as shown below: NO2 + NH3 → NH4NO3 (solid sediment) NH4NO3 → N2O + 2H2O (decomposes upon temperature fluctuation) The key to achieving cold N2O emissions lies in: 1. High NO2 concentration: The DOC located before the SCR will oxidize the NO in the exhaust gas into NO2, which will then provide raw materials for the formation of ammonium nitrate required by the SCR. 2. Temperature window: SCR catalyst activity is low at 150–250℃, NH3 cannot effectively reduce NOx, but instead reacts with NO2 to generate NH4NO3 which is deposited on the catalyst surface; 3. Triggered decomposition: When the operating conditions change (such as rapid acceleration) and the discharge temperature rises sharply, the sediment decomposes and releases N2O instantaneously.

[0048] In this embodiment of the application, high-temperature N2O emissions are mainly based on the direct oxidation pathway of ammonia, as shown below: 4NH3 + 3O2 → 2N2O + 6H2O (side reaction) 4NH3 + 5O2 → 4NO + 6H2O (a more violent side reaction) The key to achieving high-temperature N2O emissions lies in: 1. Excess NH3: To achieve high NOx conversion efficiency, urea is often over-sprayed, with an NH3 / NOx molar ratio > 1.05; 2. High temperature (e.g., temperature > 400℃): When the catalyst activity is too high, the main SCR reaction (reduction) competes with the side reaction (oxidation), and some NH3 is oxidized by O2 to N2O instead of N2.

[0049] The above comparison shows that the formation of cold N2O needs to be suppressed from the raw material end (NO2), while the formation of high-temperature N2O needs to be suppressed from the dosage end (NH3).

[0050] In some specific embodiments, in the existing "DOC+DPF+SCR&ASC" series aftertreatment system, all exhaust gas passes through the DPF, which consumes NO2 (passive regeneration reaction: C + 2NO2 → CO2 + 2NO), easily leading to insufficient NO2 in the subsequent SCR and failing to leverage the advantages of rapid SCR. However, in this application, by constructing a dual-pathway system (i.e., the first and second branches mentioned above), the DOC in the second branch can be dedicated to producing NO2, increasing the NO2 ratio before DDPF from 10% to 30-50%. This satisfies both the passive regeneration consumption of DDPF and ensures sufficient NO2 for SCR to activate the rapid reaction, as detailed below: DPF / DDPF has two regeneration methods: Active regeneration: The fuel injection temperature rises to 600℃, which consumes fuel and is at a high temperature. The chemical reaction is: C + O2 → CO2 (requires 550-600℃, and the reaction is slow). Passive regeneration: Utilizes NO2 to oxidize carbon soot at 250-450℃, eliminating the need for additional oil injection. Chemical reaction: C + 2NO2 → CO2 + 2NO.

[0051] In this embodiment, the DOC of the second branch can be dedicated to producing NO2, which can maximize NO2 generation. Since NO2 is a stronger oxidant, it can continuously burn off soot at normal exhaust temperatures (250-450°C), thus significantly reducing the frequency of active regeneration, saving fuel, and reducing the peak emission of regenerated PN.

[0052] Comparison of standard and rapid reactions in SCR: Standard SCR (NO only): 4NH3 + 4NO + O2 → 4N2 + 6H2O (slow reaction); Fast SCR (NO / NO2≈1:1): 2NH3+ NO + NO2→ 2N2+ 3H2O (rate increased by 10 times); In this embodiment, the DOC of the second branch can be dedicated to producing NO2, which can maximize NO2 generation, promote the rapid reaction of SCR, and enable the reaction of NH3 and NOx to be carried out at a lower temperature (150-200℃ can be started) and at a higher efficiency.

[0053] In some specific embodiments, the particulate matter capture module 105 includes a composite catalytic converter DDPF (DOC onDPF), wherein the composite catalytic converter refers to coating the surface of the intake end channel of the diesel particulate filter DPF with a diesel oxidation catalytic coating DOC, forming a series structure of a front-end oxidation zone and a rear-end capture zone.

[0054] In this embodiment, due to the construction of two branches, when the particulate filter DPF has a high carbon load and requires active regeneration, the fuel injection may generate two HC leakage sources: First branch HC leakage: When the engine is cold-started or under low load, combustion is incomplete, and the original engine emits HC; and during active regeneration, since there is no HC oxidation device in the first branch, HC leakage also occurs. The second branch of HC leakage: DOC is responsible for HC oxidation, but DOC's oxidation efficiency is not 100%, which leads to some HC leakage; If these leaked HCs directly enter the subsequent SCR stage, they will cause coking and carbon buildup on the surface of the SCR catalyst, reducing its activity, increasing the emission of greenhouse gases such as CH4 and C3H8, and potentially leading to side reactions and the production of harmful products.

[0055] In this embodiment, the traditional DPF is replaced with DDPF (DOC on DPF), and a DOC catalyst is coated at the front end of the DPF. This allows HC leaked from both branches to be treated secondary by the DDPF, and the DOC in the second branch only needs to treat the HC in that branch, thus significantly reducing its load. Furthermore, even if the oxidation efficiency of the DOC in the second branch decreases due to carbon buildup or aging, the DDPF can act as a safety net to handle the remaining HC.

[0056] In some specific embodiments, for any one of the first nitrogen oxide purification module 103 and the second nitrogen oxide purification module 106, the nitrogen oxide purification module includes a selective catalytic reduction (SCR) and an ammonia purifier (ASC) connected in series; the selective catalytic reduction is used to purify nitrogen oxides in exhaust gas; the ammonia purifier is used to purify ammonia generated by the selective catalytic reduction during the process of purifying nitrogen oxides.

[0057] Specifically, the first nitrogen oxide purification module 103 is as follows: Figure 2 The front-end SCR & ASC, and the second nitrogen oxide purification module 106, are as follows: Figure 2 The backend SCR & ASC in the middle.

[0058] In some specific embodiments, the first urea injection mixing module 102 includes a first urea injection device and a first mixer, for example... Figure 2 The "urea injection 1 and mixer" are installed at the input of the pre-stage SCR&ASC; the second urea injection mixing module 109 includes a second urea injection device and a second mixer, for example... Figure 2 The "urea injection 2 and mixer" are set at the input of the SCR & ASC in the middle stage.

[0059] In the embodiments of this application, the SCR catalytic reaction is essentially the reaction of ammonia (NH3) with nitrogen oxides (NO3). X The selective reduction reaction of ammonia is necessary, but the vehicle system cannot directly carry high-pressure ammonia gas (which is highly toxic, corrosive, and has a high storage risk). Therefore, urea aqueous solution is used as a safe and stable liquid precursor.

[0060] The core purpose of setting up a urea injection device and mixer before the SCR (Selective Catalytic Reduction) is to efficiently convert the urea aqueous solution into a uniformly distributed ammonia gas (NH3), providing an ideal reducing agent concentration field for the SCR catalytic reaction, as shown below: Urea droplets decompose into ammonia and isocyanic acid (HNCO) at temperatures above 180°C, as shown in the following chemical formulas: CO(NH2)2→ NH3+ HNCO HNCO further reacts with water vapor to produce NH3, which is used as a reducing agent in the SCR catalytic reaction. HNCO + H2O → NH3 + CO2 The purpose of the mixer is to completely decompose uric acid into NH3 and distribute it evenly (e.g., NH3 uniformity at the front cross-section of the SCR carrier >95%) in the exhaust gas. Inhomogeneity can cause the following problems: localized excessive NH3 concentration → ammonia leakage (>10ppm), localized dilution → NO. X Conversion efficiency <70%.

[0061] The catalytic reaction stages of SCR (Selective Catalytic Reduction) are as follows: NH3 and NO X Selective reduction occurs on the surface of copper / iron zeolite catalysts, and the main reactions are: Standard reaction (stoichiometric ratio 1:1) 4NO + 4NH3 + O2 → 4N2 + 6H2O When the NO2 concentration is low, more than 90% of NO... X This path was used to restore the original state.

[0062] Rapid response (requires NO2) NO + NO2 + 2NH3 → 2N2 + 3H2O When DOC provides NO2 so that NO / NO2≈1:1, the reaction rate increases by 17 times, which is the key to efficient operation in the low-temperature range (180-250℃).

[0063] In some specific embodiments, the engine is a diesel engine.

[0064] In some specific embodiments, the pollutant pre-purification module 104 includes a diesel oxidation catalyst (DOC) for converting carbon monoxide (CO), hydrocarbons (HC), and some particulate matter (PM) in diesel engine exhaust into carbon dioxide (CO2) and water (H2O) through catalytic oxidation reactions, and oxidizing NO to NO2.

[0065] The parallel aftertreatment system provided in this application embodiment adds a front-stage SCR&ASC and DOC in parallel. Compared with the original traditional DOC+DPF+SCR&ASC aftertreatment system, it does not increase the length of the aftertreatment system and is convenient for vehicle layout.

[0066] Corresponding to the above parallel post-processing systems (e.g.) Figure 1 , 2 As shown in the figure, this application also provides a control method for a parallel post-processing system. Figure 3 As shown, the control method of this parallel after-processing system includes: Step S201: After the engine starts, the first temperature of the first temperature measuring module 101, the second temperature of the second temperature measuring module 107, and the first nitrogen oxide concentration of the nitrogen oxide concentration sensor 108 are obtained, and the second nitrogen oxide concentration of the engine exhaust pipe is calculated according to the engine operating parameters.

[0067] In some specific embodiments, the engine operating parameters include at least one of the following: engine speed, engine torque, fuel injection quantity, and fuel injection timing.

[0068] In some specific embodiments, a nitrogen oxide concentration prediction model can be trained based on multiple historical data sets. The current engine operating parameters are then input into the trained nitrogen oxide concentration prediction model to obtain the nitrogen oxide concentration in the engine exhaust pipe at the current moment. Each historical data set includes multiple engine operating parameters for the corresponding time period, and the corresponding nitrogen oxide concentration. The nitrogen oxide concentration prediction model is not a key technical focus in this application embodiment and is not specifically limited thereto.

[0069] Step S202, compare the magnitudes of the first temperature, the second temperature, and the urea injection start temperature.

[0070] Specifically, in the embodiments of the present application, the magnitude relationships among the first temperature, the second temperature, and the urea injection start temperature are mainly divided into three cases: 1. The first temperature T1 is greater than the urea injection start temperature Ton, and the second temperature T2 is less than the urea injection start temperature Ton, that is, T1 > Ton and T2 < Ton; 2. The first temperature T1 is greater than the urea injection start temperature Ton, and the second temperature T2 is greater than the urea injection start temperature Ton, that is, T1 > Ton and T2 > Ton; 3. Other cases.

[0071] Step S203, if the first temperature is greater than the urea injection start temperature, and the second temperature is less than the urea injection start temperature, calculate the first urea injection amount according to the second nitrogen oxide concentration and the exhaust gas flow rate of the engine exhaust pipe, and control the first urea injection device to inject according to the first urea injection amount, while keeping the second urea injection device closed.

[0072] Specifically, as Figure 4 shown: when T1 > Ton and T2 < Ton, the first urea injection device can be opened and the second urea injection device can be closed. Among them, the first urea injection amount of the first urea injection device can be calculated according to the second nitrogen oxide concentration and the exhaust gas flow rate of the engine exhaust pipe.

[0073] In some specific embodiments, the first urea injection amount can be calculated by the following method: m1 = 0.5 * ANRdes1 * NOx_virtual * Q * C where, m1 represents the first urea injection amount; ANRdes1 represents the target ammonia-nitrogen molar ratio (NH3 / NOx) of the pre-stage SCR, 0.5 < ANRdes1 < 1; NOx_virtual represents the second nitrogen oxide concentration, Q represents the exhaust gas flow rate in the exhaust pipe, and C represents the conversion coefficient; Step S204, if the first temperature is greater than the urea injection start temperature, and the second temperature is greater than the urea injection start temperature, calculate the first urea injection amount according to the second nitrogen oxide concentration and the exhaust gas flow rate of the engine exhaust pipe, and calculate the second urea injection amount according to the first nitrogen oxide concentration and the exhaust gas flow rate of the engine exhaust pipe; control the first urea injection device to inject according to the first urea injection amount, and control the second urea injection device to inject according to the second urea injection amount.

[0074] Specifically, as Figure 4As shown: when T1>Ton and T2>Ton, the first urea injection device and the second urea injection device can be turned on. Among them, the first urea injection amount of the first urea injection device can be calculated according to the second nitrogen oxide concentration and the exhaust gas flow rate of the engine exhaust pipe, and the second urea injection amount of the second urea injection device can be calculated according to the first nitrogen oxide concentration and the exhaust gas flow rate of the engine exhaust pipe.

[0075] In some specific embodiments, the second urea injection amount can be calculated by the following method: m2=ANRdes2*NOx_sensor*Q*C Where, m2 represents the second urea injection amount; ANRdes2 represents the target ammonia-nitrogen molar ratio (NH3 / NOx) of the post-stage SCR, 0.2<ANRdes1<0.7; NOx_sensor represents the first nitrogen oxide concentration, Q represents the exhaust gas flow rate in the exhaust pipe, and C represents the conversion coefficient.

[0076] In some specific embodiments, when the magnitude relationship between the first temperature, the second temperature and the urea injection start temperature is other situations, both the first urea injection device and the second urea injection device are turned off.

[0077] In the embodiment of the present application, the second branch (i.e., the branch containing DOC) is used to oxidize NO in the exhaust gas of this branch into NO2 to increase the proportion of NO2 before DDPF, promote the passive regeneration of DDPF and increase the reaction rate of the post-stage SCR. When the carbon loading of DDPF reaches the limit value and active regeneration is required, the ECU calculates the amount of fuel required for regeneration. The DOC branch is used to oxidize a part of HC to increase the inlet temperature of DDPF, and DDPF is used to treat the HC leaked from the SCR branch to reduce the temperature gradient of the DDPF carrier.

[0078] In the embodiment of the present application, as Figure 2 shown, a pre-stage SCR is set before DDPF. The pre-stage SCR treats most of the NOx. Because it is close to the engine, the NOx concentration is high and the temperature is high, and the conversion efficiency can reach 90-95%; the post-stage SCR set after DDPF only needs to treat the residual NOx, the load is reduced by 70-80%, and the urea injection amount is greatly reduced, which can greatly reduce the pressure of the post-stage SCR and improve the emission robustness of the system. And the PN generated by the urea injection of the pre-stage SCR can be captured by DDPF to reduce the PN emission of the system. In addition, the NO2 concentration at the inlet of the pre-stage SCR is low (the proportion of NO2 in the original engine emissions is very small), which reduces the generation of N2O at low temperatures; the urea injection amount of the post-stage SCR is reduced, which reduces the generation of N2O at high temperatures.

[0079] In this embodiment, DDPF can be used to treat HC leaked in the SCR branch during active regeneration of the particulate filter, while also working with DOC to improve the passive regeneration efficiency of the particulate filter, reduce the temperature gradient during active regeneration of DDPF, and reduce the total amount of precious metals used in DOC and DDPF; it also increases the NO2 ratio before the subsequent SCR and improves the SCR reaction rate (promoting the occurrence of fast SCR reactions).

[0080] Corresponding to the above implementation methods for the control of parallel post-processing systems, this application also provides a control device for a parallel post-processing system, used to execute the control method for the parallel post-processing system described in any of the above embodiments. For example... Figure 5 As shown, the control device of the parallel post-processing system includes: The temperature measurement module is used to acquire the first temperature of the first temperature measurement module 101, the second temperature of the second temperature measurement module 107, and the first nitrogen oxide concentration of the nitrogen oxide concentration sensor 108 after the engine is started, and to calculate the second nitrogen oxide concentration of the engine exhaust pipe based on the engine operating parameters; the engine operating parameters include at least one of the following: engine speed, engine torque, fuel injection quantity, and fuel injection timing. A temperature comparison module is used to compare the magnitudes of the first temperature, the second temperature, and the urea spraying temperature. The urea injection module is used to calculate the first urea injection quantity based on the second nitrogen oxide concentration and the exhaust flow rate of the engine exhaust pipe if the first temperature is greater than the urea injection temperature and the second temperature is less than the urea injection temperature, and control the first urea injection device to inject according to the first urea injection quantity, while keeping the second urea injection device closed.

[0081] Optionally, the urea injection module is further configured to: calculate a first urea injection quantity based on a second nitrogen oxide concentration and an exhaust flow rate of the engine exhaust pipe, and calculate a second urea injection quantity based on a first nitrogen oxide concentration and an exhaust flow rate of the engine exhaust pipe, if the first temperature is greater than the urea injection temperature and the second temperature is greater than the urea injection temperature; control the first urea injection device to inject urea according to the first urea injection quantity; and control the second urea injection device to inject urea according to the second urea injection quantity.

[0082] The control device for the parallel post-processing system provided in the above embodiments of this application and the control method for the parallel post-processing system provided in the embodiments of this application are based on the same inventive concept and have the same beneficial effects as the methods adopted, run or implemented by the application programs stored therein.

[0083] This application also provides a computer device for executing the control method of the above-described parallel post-processing system. Please refer to... Figure 6 This illustrates a schematic diagram of a computer device provided by some embodiments of this application. For example... Figure 6 As shown, the computer device 6 includes: a processor 600, a memory 601, a bus 602, and a communication interface 603. The processor 600, the communication interface 603, and the memory 601 are connected via the bus 602. The memory 601 stores a computer program that can run on the processor 600. When the processor 600 runs the computer program, it executes the control method of the parallel post-processing system provided in any of the foregoing embodiments of this application.

[0084] The memory 601 may include high-speed random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Communication between this system network element and at least one other network element is achieved through at least one communication interface 603 (which can be wired or wireless), such as the Internet, wide area network, local area network, or metropolitan area network.

[0085] Bus 602 can be an ISA bus, PCI bus, or EISA bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. The memory 601 is used to store programs. After receiving an execution instruction, the processor 600 executes the program. The control method of the parallel post-processing system disclosed in any of the foregoing embodiments can be applied to the processor 600, or implemented by the processor 600.

[0086] The processor 600 may be an integrated circuit chip with signal processing capabilities. In implementation, each step of the above method can be completed by the integrated logic circuitry in the hardware of the processor 600 or by instructions in software form. The processor 600 may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an off-the-shelf programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules may reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. The storage medium is located in memory 601. Processor 600 reads the information in memory 601 and, in conjunction with its hardware, completes the steps of the above method.

[0087] The computer device provided in this application embodiment and the control method of the parallel post-processing system provided in this application embodiment are based on the same inventive concept and have the same beneficial effects as the methods they adopt, operate or implement.

[0088] This application also provides a computer-readable storage medium corresponding to the control method for the parallel post-processing system provided in the foregoing embodiments. Please refer to... Figure 7 The computer-readable storage medium shown is an optical disc 30, on which a computer program (i.e., a program product) is stored. When the computer program is run by a processor, it executes the control method of the parallel post-processing system provided in any of the foregoing embodiments.

[0089] It should be noted that examples of the computer-readable storage medium may also include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other optical and magnetic storage media, which will not be elaborated here.

[0090] The computer-readable storage medium provided in the above embodiments of this application and the control method of the parallel post-processing system provided in the embodiments of this application are based on the same inventive concept and have the same beneficial effects as the methods adopted, run or implemented by the application programs stored therein.

[0091] It should be noted that: Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of this application may be practiced without these specific details. In some instances, well-known structures and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0092] Similarly, it should be understood that, for the sake of brevity and to aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of this application, various features of this application are sometimes grouped together in a single embodiment, figure, or description thereof. However, this disclosure should not be construed as reflecting a schematic diagram in which the claimed application requires more features than expressly recited in each claim. Rather, as reflected in the following claims, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of this application.

[0093] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0094] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A parallel post-processing system, characterized in that, The parallel aftertreatment system includes a first branch and a second branch arranged in parallel. The input ends of the first branch and the second branch are used to connect to the engine exhaust pipe. A first temperature measuring module (101) is provided between the input end and the engine exhaust pipe. The first branch is provided with a first urea injection mixing module (102) and a first nitrogen oxide purification module (103) in sequence along the exhaust flow direction; the second branch includes a pollutant pre-purification module (104); the output ends of the first branch and the second branch are connected in series with a particulate matter collection module (105) and a second nitrogen oxide purification module (106). A second temperature measuring module (107), a nitrogen oxide concentration sensor (108), and a second urea injection mixing module (109) are provided between the particulate matter collection module (105) and the second nitrogen oxide purification module (106).

2. The parallel post-processing system according to claim 1, characterized in that, The particulate matter capture module (105) includes a composite catalytic converter, which refers to coating the surface of the intake end channel of the diesel particulate filter with a diesel oxidation catalytic coating to form a series structure of the front oxidation zone and the rear capture zone.

3. The parallel post-processing system according to claim 1 or 2, characterized in that, For any one of the first nitrogen oxide purification module (103) and the second nitrogen oxide purification module (106), the nitrogen oxide purification module includes a selective catalytic reducer and an ammonia purifier connected in series. The selective catalytic reduction device is used to purify nitrogen oxides in exhaust gas; The ammonia purifier is used to purify the ammonia generated by the selective catalytic reduction unit during the purification of nitrogen oxides.

4. The parallel post-processing system according to claim 1 or 2, characterized in that, For either the first urea injection mixing module (102) or the second urea injection mixing module (109), the urea injection mixing module includes a urea injection device and a mixer.

5. The parallel post-processing system according to claim 1 or 2, characterized in that, The engine includes a diesel engine, and the pollutant pre-purification module (104) includes a diesel oxidation catalyst.

6. A control method for a parallel post-processing system, characterized in that, The control method is applied to the parallel post-processing system according to any one of claims 1 to 5; the control method includes: After the engine starts, the first temperature of the first temperature measuring module (101), the second temperature of the second temperature measuring module (107) and the first nitrogen oxide concentration of the nitrogen oxide concentration sensor (108) are obtained, and the second nitrogen oxide concentration of the engine exhaust pipe is calculated according to the engine operating parameters; the engine operating parameters include at least one of the following: engine speed, engine torque, cyclic fuel injection quantity and fuel injection timing; Compare the magnitudes of the first temperature, the second temperature, and the urea spraying temperature; If the first temperature is greater than the urea injection temperature and the second temperature is less than the urea injection temperature, the first urea injection quantity is calculated based on the second nitrogen oxide concentration and the exhaust flow rate of the engine exhaust pipe, and the first urea injection device is controlled to inject according to the first urea injection quantity, while the second urea injection device is kept closed.

7. The method according to claim 6, characterized in that, The method further includes: If the first temperature is greater than the urea injection temperature and the second temperature is greater than the urea injection temperature, then the first urea injection quantity is calculated based on the second nitrogen oxide concentration and the exhaust flow rate of the engine exhaust pipe, and the second urea injection quantity is calculated based on the first nitrogen oxide concentration and the exhaust flow rate of the engine exhaust pipe. The first urea injection device is controlled to inject urea according to the first urea injection amount, and the second urea injection device is controlled to inject urea according to the second urea injection amount.

8. A control device for a parallel post-processing system, characterized in that, The device includes: The temperature measurement module is used to acquire the first temperature of the first temperature measurement module (101), the second temperature of the second temperature measurement module (107), and the first nitrogen oxide concentration of the nitrogen oxide concentration sensor (108) after the engine is started, and to calculate the second nitrogen oxide concentration of the engine exhaust pipe according to the engine operating parameters; the engine operating parameters include at least one of the following: engine speed, engine torque, cyclic fuel injection quantity, and fuel injection timing; A temperature comparison module is used to compare the magnitudes of the first temperature, the second temperature, and the urea spraying temperature. The urea injection module is used to calculate the first urea injection quantity based on the second nitrogen oxide concentration and the exhaust flow rate of the engine exhaust pipe if the first temperature is greater than the urea injection temperature and the second temperature is less than the urea injection temperature, and control the first urea injection device to inject according to the first urea injection quantity, while keeping the second urea injection device closed.

9. A computer device, characterized in that, include: A memory and a processor are communicatively connected, the memory stores computer instructions, and the processor executes the computer instructions to perform the control method of the parallel post-processing system according to any one of claims 6 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to execute the control method of the parallel post-processing system according to any one of claims 6 to 7.

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