Commercial vehicle tail gas after-treatment device

Abstract

The invention relates to the technical field of commercial vehicle after-treatment systems, and particularly discloses a commercial vehicle tail gas after-treatment device which is characterized in that an SOC carrier assembly, a DPF carrier assembly and an SCR / ASC carrier assembly are sequentially arranged, an exhaust pipe is provided with a gas inlet end and a gas outlet end in the length direction of the exhaust pipe, the gas inlet end is used for receiving waste gas emission of an engine, the gas outlet end is communicated with a treatment box, and the treatment box is communicated with the SOC carrier assembly; the first urea nozzle is arranged on the exhaust pipe and located at the air inlet end, and the second urea nozzle is arranged on the treatment box and located between the DPF carrier assembly and the SCR / ASC carrier assembly. The first urea nozzle and the second urea nozzle are introduced to achieve double spraying, the urea atomization coverage range is enlarged, it is ensured that ammonia gas generated by decomposition is fully mixed with tail gas, and the nitrogen-oxygen conversion rate is increased. And the first urea nozzle is arranged at the gas inlet end, so that the movement track of the urea can be further prolonged, the mixing efficiency of the urea and the high-temperature tail gas is improved, hydrolysis and evaporation of the urea are promoted, and higher nitrogen and oxygen emission is matched.

Description

Technical Field

[0001] The present invention relates to the technical field of commercial vehicle aftertreatment systems, and particularly to an exhaust gas aftertreatment device for commercial vehicles. Background Art

[0003] Existing exhaust gas aftertreatment devices generally consist of four major parts: DOC (Diesel Oxidation Catalyst), DPF (Diesel Particulate Filter), SCR (Selective Catalytic Reduction), and ASC (Ammonia Oxidation Catalyst) (Diesel Oxidation Catalyst - Diesel Particulate Filter - Selective Catalytic Reduction - Ammonia Oxidation Catalyst). Through these four units, harmful pollutants in the exhaust emissions of diesel engines can be removed to obtain clean exhaust gas. However, as the thermal efficiency of diesel engines continues to increase, the corresponding original engine emissions also increase, which poses higher requirements for the nitrogen oxide conversion rate in exhaust gas aftertreatment and increases the challenge of meeting exhaust emission standards.

[0004] Therefore, there is an urgent need for an exhaust gas aftertreatment device for commercial vehicles to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide an exhaust gas aftertreatment device for commercial vehicles, which can effectively improve the nitrogen oxide conversion rate to adapt to higher original engine emissions.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides an exhaust gas aftertreatment device for commercial vehicles, comprising:

[0008] A treatment box, in which a treatment unit is encapsulated. The treatment unit includes an SOC carrier assembly, a DPF carrier assembly, and an SCR / ASC carrier assembly, and the SOC carrier assembly, the DPF carrier assembly, and the SCR / ASC carrier assembly are arranged in sequence;

[0009] An exhaust pipe, the two ends of which along its own length direction are respectively an intake end and an outlet end. The intake end is used to receive the exhaust emissions of the engine, and the outlet end is communicated with the treatment box;

[0010] A first urea nozzle, which is arranged on the exhaust pipe and is located at the intake end;

[0011] A second urea nozzle, which is arranged in the treatment box and is located between the DPF carrier assembly and the SCR / ASC carrier assembly.

[0012] As a preferred technical solution of the above-mentioned commercial vehicle exhaust aftertreatment device, the SOC carrier assembly includes an SOC front-stage module and an SOC rear-stage module arranged in sequence. The SOC front-stage module is located upstream of the SOC rear-stage module, and the SOC front-stage module includes a V-SCR module and a Cu-SCR module, and the V-SCR module is located upstream of the Cu-SCR module.

[0013] As a preferred technical solution of the above-mentioned commercial vehicle exhaust aftertreatment device, a coating composed of Cu-based and zeolite is coated on the V-SCR module, and then a coating composed of vanadium and / or Fe-based and zeolite is coated on the outside thereof. A coating composed of Cu-based and zeolite is coated on the Cu-SCR module, and a coating containing Pt and / or Pd noble metals is coated on the SOC rear-stage module.

[0014] As a preferred technical solution of the above-mentioned commercial vehicle exhaust aftertreatment device, the length of the coating composed of vanadium and / or Fe-based and zeolite coated on the outside of the V-SCR module after coating with the coating composed of Cu-based and zeolite is L1, and the length of the coating composed of Cu-based and zeolite coated on the SOC front-stage module is L2. Wherein, L1 and L2 satisfy: L1 / L2 ≤ 0.5.

[0015] As a preferred technical solution of the above-mentioned commercial vehicle exhaust aftertreatment device, the length of the coating containing Pt and / or Pd noble metals coated on the SOC rear-stage module is L3. Wherein, L1 and L3 satisfy: L1 / L3 ≤ 1.

[0016] As a preferred technical solution of the above-mentioned commercial vehicle exhaust aftertreatment device, the diameter of the SOC front-stage module is D1, and the diameter of the SOC rear-stage module is D2. Wherein, D1 and D2 satisfy: D1 = D2.

[0017] As a preferred technical solution of the above-mentioned commercial vehicle exhaust aftertreatment device, the diameter of the DPF carrier assembly is D3. Wherein, D1 and D3 satisfy: D1 / D3 ≤ 1.

[0018] As a preferred technical solution of the above-mentioned commercial vehicle exhaust aftertreatment device, the second urea nozzle is closer to the downstream of the DPF carrier assembly than the upstream of the SCR / ASC carrier assembly.

[0019] As a preferred technical solution of the above-mentioned commercial vehicle exhaust aftertreatment device, the first urea nozzle and the second urea nozzle are configured to be able to independently control urea injection.

[0020] As a preferred technical solution of the above-mentioned commercial vehicle exhaust after-treatment device, the commercial vehicle exhaust after-treatment device further includes a control unit. The urea injection amount of the first urea nozzle is controlled in an open loop, the urea injection amount of the second urea nozzle is controlled in a closed loop, and the urea injection amounts of the first urea nozzle and the second urea nozzle are coupled and controlled for the ammonia-nitrogen ratio through the control unit.

[0021] The beneficial effects of the present invention are as follows:

[0022] The present invention provides a commercial vehicle exhaust after-treatment device, which includes: a treatment box, an exhaust pipe, a first urea nozzle and a second urea nozzle. A treatment unit is encapsulated in the treatment box, and the treatment unit includes a SOC carrier assembly, a DPF carrier assembly and an SCR / ASC carrier assembly. The SOC carrier assembly, the DPF carrier assembly and the SCR / ASC carrier assembly are arranged in sequence. The two ends of the exhaust pipe along its length direction are an intake end and an outlet end respectively. The intake end is used to receive the exhaust emissions of the engine, the outlet end is communicated with the treatment box, the first urea nozzle is arranged on the exhaust pipe and is located at the intake end, and the second urea nozzle is arranged in the treatment box and is located between the DPF carrier assembly and the SCR / ASC carrier assembly. With such an arrangement, the introduction of the first urea nozzle and the second urea nozzle realizes double injection, expands the urea atomization coverage range, ensures the full mixing of the ammonia gas generated by the decomposition of urea and the exhaust gas, effectively improves the nitrogen oxide conversion rate, and adapts to higher original engine emissions. At the same time, the first urea nozzle is arranged at the intake end, which can further extend the movement trajectory of urea, effectively increase the contact area between urea and high-temperature exhaust gas, improve the mixing efficiency of urea and high-temperature exhaust gas, and promote the hydrolysis and evaporation of urea to match higher nitrogen oxide emissions. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of the commercial vehicle exhaust after-treatment device provided by the present invention.

[0024] Wherein:

[0025] 1. Treatment box;

[0026] 2. SOC carrier assembly; 21. SOC front-stage module; 211. V-SCR module; 212. Cu-SCR module; 22. SOC rear-stage module;

[0027] 3. DPF carrier assembly;

[0028] 4. SCR / ASC carrier assembly; 41. SCR module; 42. SCR / ASC module;

[0029] 5. Exhaust pipe; 6. First urea nozzle; 7. Second urea nozzle. Detailed Embodiments

[0030] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where like or similar reference numerals denote like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0031] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0032] Unless otherwise clearly specified and defined, the terms "mounted", "connected", "connected to", "fixed" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. It can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] Unless otherwise clearly specified and defined, the first feature being "above" or "below" the second feature may include the first feature and the second feature being in direct contact, or may include the first feature and the second feature not being in direct contact but being in contact through other features therebetween. Moreover, the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "below", "under" and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0034] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and through specific embodiments.

[0035] As Figure 1As shown in the figure, this embodiment provides a post-treatment device for commercial vehicle exhaust gas. The post-treatment device for commercial vehicle exhaust gas includes: a treatment box 1, an exhaust pipe 5, a first urea nozzle 6, and a second urea nozzle 7. A treatment unit is encapsulated in the treatment box 1. The treatment unit includes a SOC carrier assembly 2, a DPF carrier assembly 3, and an SCR / ASC carrier assembly 4. The SOC carrier assembly 2, the DPF carrier assembly 3, and the SCR / ASC carrier assembly 4 are arranged in sequence. The two ends of the exhaust pipe 5 along its length direction are respectively an intake end and an outlet end. The intake end is used to receive the exhaust emissions of the engine, and the outlet end is connected to the treatment box 1. The first urea nozzle 6 is arranged on the exhaust pipe 5 and is located at the intake end. The second urea nozzle 7 is arranged in the treatment box 1 and is located between the DPF carrier assembly 3 and the SCR / ASC carrier assembly 4. With such an arrangement, the introduction of the first urea nozzle 6 and the second urea nozzle 7 realizes double injection, expands the urea atomization coverage range, ensures sufficient mixing of the ammonia generated by urea decomposition and the exhaust gas, effectively improves the nitrogen oxide conversion rate, and adapts to higher original engine emissions. At the same time, the first urea nozzle 6 is arranged at the intake end, which can further extend the movement trajectory of the urea, effectively increase the contact area between the urea and the high-temperature exhaust gas, improve the mixing efficiency of the urea and the high-temperature exhaust gas, and promote the hydrolysis and evaporation of the urea to match higher nitrogen oxide emissions.

[0036] It should be noted that the injection angles of the urea of the first urea nozzle 6 and the second urea nozzle 7 can be adjusted to make the urea stay more in the central area of the air flow, reduce the direct impact contact between the urea and the inner wall of the mixing chamber, and reduce crystallization and deposition. The injection angle can be set according to actual needs and will not be further limited here.

[0037] Optionally, in order to ensure that the urea aqueous solution sprayed by the second urea nozzle 7 has enough distance for hydrolysis and evaporation before entering the SCR / ASC carrier assembly 4, the second urea nozzle 7 is arranged on the outer end side of the treatment box 1, and the second urea nozzle 7 is closer to the downstream of the DPF carrier assembly 3 than the upstream of the SCR / ASC carrier assembly 4.

[0038] In this embodiment, the first urea nozzle 6 and the second urea nozzle 7 are configured to be able to independently control urea injection.

[0039] Optionally, the post-treatment device for commercial vehicle exhaust gas further includes a control unit (ECU). The urea injection amount of the first urea nozzle 6 adopts open-loop control, and the urea injection amount of the second urea nozzle 7 adopts closed-loop control. The urea injection amounts of the first urea nozzle 6 and the second urea nozzle 7 are coupled and controlled by the control unit for the ammonia-nitrogen ratio. With such an arrangement, the control unit (ECU) accurately controls the urea injection amounts of the first urea nozzle 6 and the second urea nozzle 7, so that the molar ratio of ammonia (NH3) to NOx reaches the optimum (usually the theoretical value is ANR = 1, that is, a 1:1 reaction), realizes the maximum NOx conversion rate, and at the same time avoids ammonia leakage.

[0040] It should be noted that both the first urea nozzle 6 and the second urea nozzle 7 use conventional urea nozzles to spray urea aqueous solution. Furthermore, without considering the cost, the first urea nozzle 6 can be replaced with an electrically heated urea nozzle, which can further improve the first-stage catalytic conversion treatment effect. No further limitation is made here.

[0041] Specifically, the present embodiment exemplarily provides the following technical solution: the SOC carrier assembly 2 includes a SOC front-stage module 21 and a SOC rear-stage module 22 which are arranged in sequence, and along the flow direction of the exhaust gas, the SOC front-stage module 21 is located upstream of the SOC rear-stage module 22, and the SOC front-stage module 21 includes a V-SCR module 211 and a Cu-SCR module 212, the V-SCR module 211 is located upstream of the Cu-SCR module 212, and the V-SCR module 211 is located at the front end of the processing box 1 and close to the exhaust end of the exhaust pipe 5.

[0042] Optionally, the V-SCR module 211 is coated with a coating composed of Cu-based and zeolite, and then the outer side thereof is coated with a coating composed of vanadium and / or Fe-based and zeolite, the Cu-SCR module 212 is coated with a coating composed of Cu-based and zeolite, and the SOC rear module 22 is coated with a coating containing Pt and / or Pd precious metals. In such a configuration, the V-SCR module 211 can be arranged at a location where the exhaust temperature is relatively high, and based on the characteristics of the V-based, the N2O can be first catalytically converted and treated in a targeted manner, and at the same time, the first-stage catalytic conversion pretreatment of NOx can be targeted based on the characteristics of the V-based and Cu-based. The Cu-SCR module 212 is sequentially arranged downstream of the V-SCR module 211, and the first-stage catalytic conversion main treatment of NOx can be targeted based on the characteristics of the Cu-based. Further, the Pt and / or Pd precious metal coating on the SOC rear module 22 can be used to oxidize CO, HC, NO, etc. to improve the conversion efficiency, and at the same time, it is used to eliminate the possible escape of a very small amount of ammonia.

[0043] It should be noted that in this embodiment, the V-SCR module 211 is placed here, and there is no need to worry about the risk of secondary pollution caused by vanadium volatilization as in the National VI mainstream technology where the V-SCR module 211 cannot be arranged after the DPF carrier assembly 3.

[0044] Optionally, in order to achieve coordinated control of conversion based on N2O and NOx, the V-SCR module 211 is coated with a coating composed of Cu-based and zeolite, and then its outer side is coated with a vanadium and / or Fe-based coating composed of zeolite, and the length of the coating is L1, and the length of the coating composed of Cu-based and zeolite coated on the SOC front-stage module 21 is L2, wherein L1 and L2 satisfy: L1 / L2≤0.5.

[0045] Optionally, the length of the coating containing noble metals Pt and / or Pd on the SOC post-stage module 22 is L3, where L1 and L3 satisfy: L1 / L3 ≤ 1. This length ratio limiting condition is used to further coordinate and control N2O, NOx, and NH3 on the basis of the length limiting condition of L1 / L2 ≤ 0.5.

[0046] In this embodiment, the V-SCR module 211 and the Cu-SCR module 212 are arranged on the same carrier. According to requirements, a partition coating process technology is adopted. At the same time, based on the original engine emission level, in order to maximize cost savings, the carrier of the Cu-based can be not coated throughout. When the carrier of the Cu-based is not coated throughout, the length of the Cu-based coating satisfies: the length of the coating calculated from the outlet end of the Cu-SCR module 212 is not less than the difference between the length of the SOC pre-stage module 21 and the coating length L1 of the V-SCR module 211, ensuring that the technical requirements of the partition coating are met and there is no white carrier between the V-SCR module 211 and the Cu-SCR module 212 on the carrier. This not only ensures the original intention of coordinating and controlling N2O and NOx but also meets the minimum amount of carrier material used, achieving cost control of the commercial vehicle exhaust after-treatment device.

[0047] Optionally, to ensure that the SOC pre-stage module 21 and the SOC post-stage module 22 can be encapsulated inside the same circular iron sheet cylinder through their respective corresponding gaskets, the diameter of the SOC pre-stage module 21 is D1, and the diameter of the SOC post-stage module 22 is D2, where D1 and D2 satisfy: D1 = D2.

[0048] In this embodiment, the DPF carrier assembly 3 can be encapsulated in a circular iron sheet cylinder through a gasket adapted to it. This circular iron sheet cylinder is a detachable structure, facilitating its maintenance operation. Its front end is connected to the tail end of the circular iron sheet cylinder encapsulating the SOC carrier assembly 2 by means of a clamp, etc. Further, in order to achieve the maximum carbon loading volume on the basis of overall consideration of the layout of the SOC carrier assembly 2, the diameter of the DPF carrier assembly 3 is D3, where D1 and D3 satisfy: D1 / D3 ≤ 1.

[0049] It should be noted that the catalyst of the DPF carrier assembly 3 adopts conventional technical means, and it should be adapted to the situation where the coating containing noble metals Pt and / or Pd is coated on the SOC post-stage module 22. Further, in order to overall consider the conversion efficiency and carbon loading capacity, and / or in order to exert a greater oxidation effect of the SOC post-stage module 22, the coating of the SOC post-stage module 22 can be partially coated on the front end of the DPF carrier assembly 3. Such a change should also be regarded as not exceeding the scope of the present invention and will not be further restricted here.

[0050] In this embodiment, the SCR / ASC carrier assembly 4 includes an SCR module 41 and an SCR / ASC module 42 arranged in sequence. The SCR / ASC carrier assembly 4 preferably adopts a parallel structure inside the processing box 1, and the SCR / ASC carrier assembly 4 plays a second-stage catalytic conversion treatment effect for NOx treatment. As described above, for NOx, the amount of the first-stage catalytic conversion treatment is controlled by the amount of urea injected by the first urea nozzle 6, and the amount of the second-stage catalytic conversion treatment is controlled by the amount of urea injected by the second urea nozzle 7. The ammonia-nitrogen ratio coupling control must be carried out for both of them to finally meet the emission regulation requirements with the minimum urea consumption. Further, in order to improve the second-stage catalytic conversion treatment efficiency, a part of the front end of the Cu-SCR module 212 is coated on the rear end or all of the DPF carrier assembly 3. Such a change should also be regarded as not exceeding the scope of the present invention and will not be further limited herein.

[0051] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A commercial vehicle exhaust aftertreatment device, characterized in that, Comprising: A processing box (1), in which a processing unit is encapsulated. The processing unit includes an SOC carrier assembly (2), a DPF carrier assembly (3), and an SCR / ASC carrier assembly (4). The SOC carrier assembly (2), the DPF carrier assembly (3), and the SCR / ASC carrier assembly (4) are arranged in sequence. An exhaust pipe (5), both ends of which along its own length direction are an intake end and an outlet end respectively. The intake end is used to receive the exhaust emissions of the engine, and the outlet end is communicated with the processing box (1). A first urea nozzle (6), which is arranged on the exhaust pipe (5) and is located at the intake end. A second urea nozzle (7), which is arranged in the processing box (1) and is located between the DPF carrier assembly (3) and the SCR / ASC carrier assembly (4).

2. The post-treatment device for commercial vehicle exhaust gas according to claim 1, characterized in that The SOC carrier assembly (2) includes an SOC front-stage module (21) and an SOC rear-stage module (22) arranged in sequence. The SOC front-stage module (21) is located upstream of the SOC rear-stage module (22), and the SOC front-stage module (21) includes a V-SCR module (211) and a Cu-SCR module (212). The V-SCR module (211) is located upstream of the Cu-SCR module (212).

3. The commercial vehicle exhaust aftertreatment device according to claim 2, characterized in that, A coating composed of Cu-based and zeolite is coated on the V-SCR module (211), and then a coating composed of vanadium and / or Fe-based and zeolite is coated on its outer side. A coating composed of Cu-based and zeolite is coated on the Cu-SCR module (212), and a coating containing Pt and / or Pd precious metals is coated on the SOC rear-stage module (22).

4. The commercial vehicle exhaust aftertreatment device according to claim 3, wherein, The length of the coating composed of Cu-based and zeolite coated on the V-SCR module (211), and then a coating composed of vanadium and / or Fe-based and zeolite coated on its outer side is L1, and the length of the coating composed of Cu-based and zeolite coated on the SOC front-stage module (21) is L2. Wherein, L1 and L2 satisfy: L1 / L2 ≤ 0.

5.

5. The commercial vehicle exhaust aftertreatment device according to claim 4, characterized in that, The length of the coating containing Pt and / or Pd precious metals coated on the SOC rear-stage module (22) is L3. Wherein, L1 and L3 satisfy: L1 / L3 ≤ 1.

6. The commercial vehicle exhaust aftertreatment device according to claim 2, wherein The diameter of the SOC front-stage module (21) is D1, and the diameter of the SOC rear-stage module (22) is D2. Wherein, D1 and D2 satisfy: D1 = D2.

7. The post-treatment device for commercial vehicle exhaust gas according to claim 6, characterized in that, The diameter of the DPF carrier assembly (3) is D3. Wherein, D1 and D3 satisfy: D1 / D3 ≤ 1.

8. The commercial vehicle exhaust aftertreatment device according to any one of claims 1-7, characterized in that, The second urea nozzle (7) is closer to the downstream of the DPF carrier assembly (3) compared to the upstream of the SCR / ASC carrier assembly (4).

9. The commercial vehicle exhaust aftertreatment device according to any one of claims 1-7, characterized in that, The first urea nozzle (6) and the second urea nozzle (7) are configured to be able to independently control urea injection.

10. The commercial vehicle exhaust aftertreatment device according to claim 9, characterized in that, The commercial vehicle exhaust aftertreatment device further includes a control unit. The urea injection amount of the first urea nozzle (6) is controlled in an open-loop manner, and the urea injection amount of the second urea nozzle (7) is controlled in a closed-loop manner. The urea injection amounts of the first urea nozzle (6) and the second urea nozzle (7) are subjected to ammonia-nitrogen ratio coupling control through the control unit.

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