CN109723529B

CN109723529B - Tail gas pipe assembly and tail gas treatment system

Info

Publication number: CN109723529B
Application number: CN201711037860.2A
Authority: CN
Inventors: 亓平; C·德林; 丁宁宁
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2017-10-30
Filing date: 2017-10-30
Publication date: 2022-09-06
Anticipated expiration: 2037-10-30
Also published as: CN109723529A

Abstract

The application provides a tail gas pipe assembly, including tail gas head tube, hybrid tube and tail gas back tube, the tail gas head tube sets to and can make tail gas flow into with first class the hybrid tube, be connected with the sprayer on the tail gas pipe assembly, the sprayer sprays combustible fluid in to the hybrid tube with the second flow direction, further be provided with the protection shield in the tail gas pipe assembly, the protection shield is the fretwork board, along first class to set up in the upper reaches of sprayer.

Description

Tail gas pipe assembly and tail gas treatment system

Technical Field

The present application relates to a vehicle vent-pipe assembly and tail gas processing system, especially relates to a vent-pipe assembly and tail gas processing system for diesel vehicle tail gas.

Background

After combustion, a diesel engine generates a large amount of exhaust gas, which cannot be directly discharged into the air and needs to be treated to a certain extent before being discharged into the air. The treatment of exhaust gas is generally accomplished by using a Diesel Oxidation Catalyst (DOC) and a particulate filter (DPF). Along with the operation of the engine, more and more particles are arranged on the DPF, the carbon deposition of the whole catalytic converter reaches a state close to saturation, the capture efficiency of the carbon particles is greatly reduced, the excessive particulate matter in tail emission is easily caused, meanwhile, the backpressure of the catalytic converter is greatly increased, and the fuel consumption rate of the engine is directly increased.

In order to remove the carbon particles in the diesel particle collector DPF, the diesel particle collector DPF needs to be regenerated in time to restore its function. DPF regeneration is divided into active regeneration and passive regeneration. The principle of active regeneration is that hydrocarbon injection, namely fuel injection, is generally added before DOC, hydrocarbon in diesel oil is combusted under the action of a DOC catalyst, so that the temperature of tail gas is increased to about 620 ℃, carbon particles in a diesel particle collector DPF are combusted at high temperature, generated carbon dioxide and other gases are discharged from a tail gas pipe along with the tail gas, and the function of the diesel particle collector DPF is recovered.

However, in the prior art, the direction of the tail gas flowing into and the injection direction of the injector form a certain included angle, the diesel particles injected by the direct impact of the tail gas flowing into the injector are deviated to one side and cannot be uniformly distributed, so that the temperature of the tail gas after combustion is not uniform, and the DPF is easily over-temperature or fails due to thermal stress.

Disclosure of Invention

An object of this application is to provide a tail gas pipe assembly, it can improve the homogeneity and the stability that the fluid that spouts distributes in the tail gas pipe.

Another object of the present application is to provide an exhaust gas treatment system, which can make the exhaust gas in the exhaust pipe have better temperature distribution after DOC.

The present application additionally provides an exhaust gas treatment system, including as above the exhaust pipe assembly, be connected with oxide reduction device and diesel particulate collector behind the exhaust pipe.

Use the exhaust pipe subassembly that this application provided, the homogeneity and the stability improvement of its distribution of jet fluid in the exhaust pipe, there is better distribution at the temperature behind the DOC in the exhaust treatment system.

Drawings

Exemplary embodiments of the present application will be described in detail below with reference to the attached drawings, it being understood that the following description of the embodiments is only for the purpose of explanation and not limitation of the scope of the present application, and wherein:

FIG. 1 is a perspective view of one embodiment of an exhaust tube assembly of the present application;

FIG. 2 is a perspective view of another angle of the tailpipe assembly shown in FIG. 1;

FIG. 3 is a cross-sectional view of one embodiment of the tailpipe assembly of the present application to show the position of the protective plate inside the mixing tube;

FIG. 4 is a perspective view of one embodiment of a protective plate in the tailpipe assembly of the present application, showing the hollowed-out structure on the protective plate;

FIG. 5 is a plan view of an embodiment of the exhaust treatment system of the present application to show the overall structure of the exhaust treatment system.

Detailed Description

In different drawings, the same or similar components are denoted by the same reference numerals.

It should be understood that the drawings are for illustrative purposes only and that the dimensions, proportions and number of parts are not intended to limit the present application.

The invention relates to an exhaust gas aftertreatment system for the aftertreatment of exhaust gases of a diesel engine, which exhaust gases, after combustion in a combustion chamber of the diesel engine, are discharged via an exhaust gas line, the main constituents of the exhaust gases being HC, CO ₂ ，NO，NO ₂ And SO ₂ . Through the exhaust pipe, the exhaust gas enters the DOC for treatment. The DOC includes a DOC support and a catalyst, which is typically a precious metal. The exhaust gas discharged through the exhaust pipe is catalyzed by the catalyst to react with oxygen in the exhaust gas at the DOC, and the basic reaction formula is as follows:

2NO+O ₂ ＝2NO ₂ ；

SO ₂ +1/2O ₂ ＝SO ₃

4HC+3O ₂ ＝2CO ₂ +2H ₂ O

2CO+O ₂ ＝2CO ₂

however, the advance of the chemical reaction is that the temperature must reach the ignition temperature of the DOC, which is approximately 200 degrees or more. Furthermore, if more sulfate is coated on the noble metal as a catalyst, DOC is poisoned and loses its function.

A diesel Particulate trap, which may be POC (Particulate oxidation Catalyst) or dpf (diesel Particulate filter), is also connected to the rear of the DOC. The diesel particulate trap may trap carbon particulates in the diesel fuel that may react with NO flowing from the DOC after certain conditions ₂ Carrying out a reaction of the formula:

2C+3NO ₂ ＝CO+CO ₂ +3NO

this reaction is generally referred to as a Continuous Regeneration reaction (CRT). CRT generally needs higher reaction temperature (300-500degc), if the temperature is not up to the initial temperature of the reaction, carbon particles are accumulated on POC or DPF for a long time, which can cause the blockage, the non-function, the high back pressure and the engine non-ignition.

However, when a vehicle runs in a city with traffic congestion, the diesel engine is in a low-speed running state for a long time, so that the temperature of exhaust gas in the exhaust passage is lower than 200 ℃ when the exhaust gas reaches the DOC, the ignition temperature of the DOC is not reached, the DOC is very easy to be poisoned and loses functions, and NO (or less) NO is generated ₂ The CRT reaction in the diesel particulate trap does not occur in the form of N, and carbon particles in the diesel particulate trap accumulate. Eventually, the diesel particulate trap backpressure becomes too high, fuel consumption increases and the diesel particulate trap breaks down during high speed operation.

Referring to fig. 1 to 4, an exhaust pipe assembly 10 of the present application includes an exhaust front pipe 11, a mixing pipe 12 and an exhaust rear pipe 13, which are sequentially installed or integrally formed. The exhaust gas first flows into the mixing pipe 12 in a first flow direction along the exhaust gas front pipe 11. It will be understood by those of ordinary skill in the art that the exhaust pipe is typically a cylindrical pipe, although other piping is not excluded. The first flow direction is the axial direction of the exhaust gas front pipe 11, in this embodiment, the mixing pipe 12 is a bent pipe, an injector 15 is installed on the mixing pipe 12 from the outside, and the injector 15 injects diesel oil into the mixing pipe 12 in the second flow direction. Of course, in other embodiments, the injected fluid may be gasoline, natural gas, or other combustible material. The tail gas front pipe 11 and the tail gas rear pipe 12 are arranged at an obtuse angle. In the mixing pipe 12, the exhaust gas flowing in from the first flow direction and the diesel injected in the second flow direction form a mixing region D. The mixing region D is a region where the exhaust gas flow flowing in from the first flow direction intersects with the diesel particulate flow injected from the injector, and the exhaust gas and the diesel particulate are mixed in the region and then enter the exhaust gas after-pipe 13. A perforated protective plate 14 is arranged in the mixing tube 12, the protective plate 14 being arranged in the mixing tube 12 in a welded manner and being oriented upstream of the ejector 15 in the first flow direction and upstream of the mixing region D. The protective guard 14 at least partially obstructs the aforementioned mixing region D. Moreover, the protection plate 14 is preferably provided to shield a core region of the mixing region D, so that the shielding effect of the hollow protection plate 14 in the core region reduces the exhaust gas flow velocity in the region, reduces the interference of the exhaust gas flow on the diesel particle flow direction, and makes the diesel particle flow more uniformly and stably distributed in the mixing pipe 12. By core region is meant the region where the diesel particulates initially intersect the exhaust after injection, where the diesel particulates are not sufficiently dispersed and are at a high concentration. There is a gap between the guard plate 14 and the edge of the mixing tube 12 through which part of the exhaust gas passes. In this embodiment, the protective plate 14 is parallel to the second flow direction of the ejector 15, and the proportion of the total area of the non-hollowed-out area to the plane thereof is preferably 20% to 30%.

Referring to fig. 5, a schematic structural diagram of an exhaust gas treatment system according to the present application includes an exhaust pipe assembly 10, which is connected to a DOC 20 and a diesel particulate collector 30 in sequence after an exhaust gas rear pipe 13.

In operation, tail gas enters from the tail gas front pipe 11, and when the tail gas impacts the protection plate 14, turbulence is formed due to the existence of the non-hollow part, so that the flow speed of the tail gas passing through the hollow part is reduced. The protective plate 14 is arranged upstream of the mixing region D formed by the exhaust gas flow and the diesel particle flow, at least partially shielding the mixing region D, in particular the core region of the mixing region. The tail gas flow with lower speed has lower influence on the injection direction of the diesel particles, and the tail gas flow is uniformly and stably distributed in the mixing pipe 12, so that the mixing uniformity of the tail gas and the diesel particles is also increased. The protective plate 14 only shields a portion of the mixing tube 12 so that a portion of the exhaust enters the mixing tube 12 from the gap between the mixing tube 12 and the protective plate 14. The exhaust and diesel particulate streams are mixed and enter the DOC 20 through an exhaust tailpipe 13. The exhaust gas after pipe 13 is arranged after the mixing pipe 12 in the second flow direction. The diesel particulates are ignited in the DOC to increase the temperature of the exhaust gas, thereby enabling the carbon particulates accumulated in the diesel particulate trap 30 to burn, and eventually achieving the purpose of reducing the amount of carbon deposits in the diesel particulate trap 30 or regenerating the diesel particulate trap 30.

Due to the arrangement of the protection plate 14, the diesel particle flow is uniformly and stably distributed in the mixing pipe 12 and the accessories behind the mixing pipe, in addition, the diesel particle flow is more uniformly mixed with the tail gas, so that the temperature of the tail gas heated after ignition in the DOC is uniform and stable, the detection is easy, and the calibration is easy in the calibration process.

The present application has been described in connection with what is presently considered to be the most practical and preferred embodiment, and it is to be understood that the invention is not limited to the disclosed embodiment, but, on the contrary, is intended to cover various modifications, equivalents, additions and substitutions within the spirit and scope of the present application as defined by the appended claims.

Claims

1. A tailpipe assembly (10) for regenerating a diesel particulate collector (30), comprising a tailpipe (11), a mixing tube (12) and a tailpipe (13) for exhaust gas, the tailpipe (11) being arranged to allow exhaust gas to flow into the mixing tube (12) in a first flow direction, an injector (15) being connected to the tailpipe assembly (10), the injector (15) injecting a combustible fluid into the mixing tube (12) in a second flow direction, characterized in that a shielding plate (14) is further arranged in the tailpipe assembly (10), the shielding plate (14) being a hollowed-out plate arranged upstream of the injector (15) in the first flow direction, the shielding plate (14) being arranged upstream of a mixing region D where the exhaust gas intersects the combustible fluid in the second flow direction in the first flow direction to reduce interference of the exhaust gas with the flow direction of the combustible fluid, the combustible fluid is distributed uniformly and stably in the mixing pipe (12).

2. The exhaust pipe assembly (10) according to claim 1, wherein the protective plate (14) at least partially shields a core region of the exhaust passage of the mixing pipe (12).

3. The exhaust tube assembly (10) of claim 2, wherein the ratio of the non-hollowed out area of the protective plate (14) to the cross-sectional area of the mixing tube (12) in the plane of the protective plate (14) is 20% to 30%.

4. The exhaust pipe assembly (10) according to claim 1, wherein the exhaust front pipe (11) and the exhaust rear pipe (12) are arranged at an obtuse angle.

5. An exhaust pipe assembly (10) according to any of claims 1-4, wherein said mixing pipe (12) is an elbow.

6. The tailpipe assembly (10) according to any of claims 1-4, characterized in that the shielding plate (14) is arranged substantially parallel to the second flow direction of the ejector (15).

7. An exhaust pipe assembly (10) according to any of claims 1-4, wherein said injector (15) injects one or a mixture of diesel, gasoline or natural gas.

8. An exhaust pipe assembly (10) according to any of claims 1-4, wherein said protective plate (14) is welded to said mixing pipe (12).

9. An exhaust gas treatment system (100) comprising an exhaust pipe assembly (10) according to any of claims 1-8, followed by an oxide reduction device (20) and a diesel particulate trap (30) after the exhaust gas after pipe (13).