CN109162790B

CN109162790B - Compact type tail gas post-treatment system

Info

Publication number: CN109162790B
Application number: CN201810706716.1A
Authority: CN
Inventors: 孙海涛; 祁晓东; 刘强; 曹禺; 代晓军; 郑明君
Original assignee: Shanghai Nuocheng Engineering Machinery Exhaust System Co ltd
Current assignee: Shanghai Nuocheng Engineering Machinery Exhaust System Co ltd
Priority date: 2018-07-02
Filing date: 2018-07-02
Publication date: 2021-08-20
Anticipated expiration: 2038-07-02
Also published as: CN109162790A

Abstract

A compact type tail gas post-treatment system relates to the field of tail gas treatment equipment and comprises an outer cylinder, an inner cylinder, an air inlet pipe, an air outlet pipe, an air delivery pipe and a urea nozzle, wherein the inner cylinder is arranged in a cavity of the outer cylinder and comprises a reaction chamber and a mixing cavity; the mixing cavity comprises a main body section, wherein tiny air dispersing holes are uniformly distributed in the main body section, the left side of the main body section is connected with the reaction chamber, the joint of the left side of the main body section and the reaction chamber is closed, the right side of the main body section is provided with an opening and is fixed through a first partition plate, a plurality of air conveying pipes are arranged around the outer side of the main body section, and an SCR converter wrapping the reaction chamber is arranged between the inner wall of the outer barrel and the outer wall of the reaction chamber; the application provides a compact exhaust aftertreatment system, it has integrated DOC, DPF and SCR's function, has PM and PN's high efficiency of getting rid of and NOx's high conversion efficiency, compact structure, and whole length is short, small, is convenient for the whole car of non-road mobile machinery arranges.

Description

Compact type tail gas post-treatment system

Technical Field

The invention relates to the field of tail gas treatment equipment, in particular to a compact tail gas after-treatment system, and particularly relates to a diesel engine after-treatment system suitable for non-road mobile machinery.

Background

The tail gas after-treatment system is used for meeting the requirements of regulations, and the tail gas discharged by the diesel engine needs to be subjected to a series of physical and chemical reactions through the after-treatment system to achieve the purpose of reducing harmful substances in the tail gas.

Non-road mobile machinery is always a monitoring blind spot of an environmental protection department, and has the advantages of wide application range and serious standard exceeding of particulate matter emission. Since the non-road mobile machinery is old and poor in oil quality, it greatly contributes to environmental pollution, and it is described that the exhaust emission of a high-emission excavator is equivalent to 50 cars. At present, the pollutant emission limit of a diesel engine for non-road mobile machinery is more and more strict, and the national environmental protection department also needs to control the PM and PN limits while controlling NOx. Beginning in 2018, the ministry of environmental protection issued a non-road mobile machinery discharge technical request letter. After the three diesel vehicles in China, the off-road mobile machine faces embarrassment. The rule I means that China will open the license plate of the non-road mobile machinery comprehensively. Such as excavators, loaders, cranes, etc., not only means that they are more severely constrained, but also that exhaust gas management and control for non-road mobile machines is more strict! The application of the prior and post-treatment system on the diesel vehicle faces many challenges, for example, the limited arrangement space on the whole vehicle determines that the smaller the volume is better under the premise of ensuring high efficiency and diesel engine performance, because the PN limit value is increased in the fourth stage of the non-road country, the scheme of selecting the SCR technical route by part of vehicles needs to be adjusted, and DPF components need to be added, the overall volume of the post-treatment system is increased a lot, so that the arrangement and installation of the post-treatment system are very difficult, most non-road mobile machines need to change the frame shape to arrange the DOC + DPF + SCR scheme, so that a lot of design change work and cost increase of the non-road mobile machines can be caused, and meanwhile, how to improve the spraying quality of the urea solution, promote the mixing uniformity of spraying and exhaust gas, make the decomposition of urea more sufficient is also one of the problems to be solved urgently. At present, according to the actual emission condition and the application range of a diesel engine, an aftertreatment system can integrate DOC, DPF, SCR and other components, the gas trend of the aftertreatment system and the arrangement mode of a single component are various, but most of the aftertreatment systems are not compact enough, and the defect that the mixing uniformity of urea spray and exhaust gas is poor exists.

Grant publication number CN204783188U, name: a Chinese utility model patent of an integrated post-treatment device comprises a cylinder body with two sealed end parts, wherein a clapboard which divides the inner cavity of the cylinder body into an air inlet cavity and an air outlet cavity is arranged in the cylinder body, an inlet pipe is arranged on the air inlet cavity, an outlet pipe is arranged on the air outlet cavity, a first post-treatment module is arranged in the air inlet cavity, a second post-treatment module is arranged in the air outlet cavity, a urea solution mixing pipe is arranged on the cylinder body, a urea nozzle is arranged on the urea solution mixing pipe, one end part of the urea solution mixing pipe is communicated with the air inlet cavity and is positioned on the left side of the first post-treatment module, and the other end part of the urea solution mixing pipe is communicated with the air outlet cavity and is positioned on the right side of the second post-treatment module; although the volume of the post-processing device is reduced, the whole vehicle is convenient to install, the whole length is still longer, the volume is not small enough, and the post-processing device is difficult to be applied to non-road mobile machinery with short wheelbase and narrow installation space.

Grant publication number CN203050864U, name: the utility model provides a Chinese utility model patent of SCR aftertreatment muffler assembly, it includes muffler casing and SCR aftertreatment ware, the tip of muffler casing is provided with intake pipe and outlet duct, has the kuppe through baffle fixed mounting in the muffler casing, and the entrance point and the intake pipe of kuppe are linked together, and the induction zone of kuppe is the toper, and it is crescent along gaseous the place ahead that advances, and SCR aftertreatment ware is located between the toper induction zone and the exit end of kuppe, and the maximum diameter of kuppe is less than the diameter of muffler casing, and the length of kuppe is less than the length of muffler casing. Its simple structure is compact, convenient and practical, and it is easy to make to transversely arrange on whole car, it is less to occupy vertical space, is favorable to short wheel base motorcycle type to arrange, but its function is fairly simple, only carries out the SCR to tail gas and handles, and does not also provide improvement scheme to the defect that how to promote spraying and exhaust mixing homogeneity.

Disclosure of Invention

In order to solve one of the deficiencies in the prior art, the application provides a compact exhaust aftertreatment system, which integrates the functions of DOC, DPF and SCR, has high removal efficiency of PM and PN and high conversion efficiency of NOx, has compact structure, short overall length and small volume, and is convenient for arrangement of a whole non-road mobile machine.

In order to achieve the technical effects, the specific technical scheme of the invention is as follows:

a compact type tail gas post-treatment system comprises an outer cylinder, an inner cylinder, an air inlet pipe, an air outlet pipe, an air delivery pipe and a urea nozzle, wherein the left side and the right side of the outer cylinder are closed, the air inlet pipe and the air outlet pipe are arranged on the left side of the outer cylinder, and the urea nozzle is arranged on the right side of the outer cylinder; the inner cylinder is arranged in the cavity of the outer cylinder and comprises a reaction chamber and a mixing cavity, the left end of the reaction chamber is connected with the tail end of the air inlet pipe, and a DOC converter and a DPF filter are arranged in the inner cavity of the reaction chamber from left to right; the mixing cavity comprises a main body section, wherein tiny air dispersing holes are uniformly distributed in the main body section, the left side of the main body section is connected with the reaction chamber, the joint of the left side of the main body section and the reaction chamber is closed, the right side of the main body section is provided with an opening and is fixed through a first partition plate, a first fixing hole for allowing the right side of the main body section to pass through and fix is formed in the first partition plate, a plurality of air conveying pipes are arranged around the outer side of the main body section, the left end of each air conveying pipe is communicated with the reaction chamber, the right end of each air conveying pipe is fixed in a corresponding first air outlet hole formed in the first partition plate, and an SCR converter wrapping the reaction chamber is arranged between the inner wall of the outer barrel and the outer wall of the reaction chamber; the flow direction of tail gas through the system is as follows: the urea enters from the air inlet pipe, passes through the DOC converter and the DPF filter in the reaction chamber rightwards, then passes through the air delivery pipe rightwards to be mixed with urea spray sprayed from the urea nozzle, then returns leftwards to enter the mixing cavity to be fully mixed and dispersed through the air dispersing holes, and finally continuously passes through the SCR converter leftwards along the space between the inner wall of the outer barrel and the outer wall of the reaction chamber and is discharged through the air outlet pipe.

Further, reaction chamber, mixing chamber are the hollow tube, and the pipe diameter of mixing chamber is less than the pipe diameter of reaction chamber, mixing chamber coaxial arrangement.

Furthermore, a contraction section is further arranged between the reaction chamber and the mixing cavity, the diameter of the contraction section is gradually reduced from left to right, one side with the large diameter is connected with the reaction chamber, and the inclined side wall of the contraction section is provided with second air outlets, the number of which corresponds to the number of the air conveying pipes. We are through establishing a contraction section between reacting chamber and hybrid chamber, the contraction section reduces from a left side to right bore gradually, makes tail gas pass through DOC converter, DPF filter back gas concentration in the contraction section on the one hand, rethread second venthole is changeed and is got into the gas-supply pipe, has improved gaseous mobility greatly, and on the other hand contraction section bore reduces gradually, can know the tail gas velocity of flow increase according to hydrodynamics analysis to pass the gas-supply pipe with higher velocity of flow and mix with urea spraying, make the mixture more abundant.

Further, the mixing chamber still includes an edge section, main part section is connected on edge section left side, edge section is for having certain length's hollow tube, edge section right side is fixed through the second baffle, be equipped with on the second baffle and be used for edge section right side to pass, fixed second fixed orifices, encircle around being equipped with a plurality of third venthole around the second fixed orifices, the quantity of third venthole is more than the quantity of first venthole. After the edge section and the second partition plate are arranged, the first partition plate, the second partition plate and the edge section jointly form a narrow closed space, the number of the third air outlet holes is more than that of the first air outlet holes, the number of the third air outlet holes is several times that of the first air outlet holes during actual design, tail gas is sprayed out through the third air outlet holes in the second partition plate at a high speed, the air flow is more uniform, the flow speed is further improved, and the tail gas and urea spray are mixed more fully and uniformly.

Furthermore, each third air outlet is also provided with a flow deflector which is an upwelled spherical cover plate, the flow deflector and the third air outlet form an oblique air jet for obliquely jetting the tail gas, and all the oblique air jets are arranged along the clockwise direction or the anticlockwise direction. We still design the water conservancy diversion piece of this structure on the third venthole especially, on the one hand because all slant fumaroles all set up along clockwise or anticlockwise, and spun tail gas forms the rotatory vortex along same direction for tail gas and urea spraying mix more fully, and on the other hand water conservancy diversion piece also plays and prevents that urea spraying or its gas after mixing with tail gas from entering into in first baffle, second baffle and the marginal section forms a narrow and small confined space jointly.

Furthermore, the contraction section, the main body section and the edge section are of a funnel-shaped integrated structure, and a plug is arranged at the joint of the contraction section and the main body section for plugging.

Furthermore, the intake pipe is hopper-shaped, and including a horizontal circle pipeline section and an expansion section, the expansion section increases from a left side to right bore gradually, and one side that its bore is big is connected with the reaction chamber. We design into the hourglass shape of bore crescent with the intake pipe, make tail gas pass through the intake pipe and get the diffusion on the one hand, and the area of contact of tail gas and DOC converter increases, has improved the purification efficiency of tail gas, and on the other hand knows the tail gas velocity of flow according to hydrodynamics analysis and reduces, and the reaction time that tail gas passes through DOC converter, DPF filter is more sufficient for tail gas purification is more abundant.

Furthermore, the expansion section, the contraction section and the reaction chamber are respectively in detachable threaded connection. The removable threaded connection mode makes things convenient for the equipment, the dismantlement and the clearance of each part of inner tube, makes things convenient for DOC converter, DPF filter's change and clearance simultaneously.

Furthermore, the inner cylinder and the outer cylinder are coaxially arranged, a space is reserved between the inner cylinder and the inner wall of the outer cylinder, and the urea nozzle is arranged on the right side of the outer cylinder and directly faces the center of the mixing cavity. Because the tail gas is scattered outwards and around through the gas scattering holes, the flow of the tail gas to the space between the inner wall of the outer barrel and the outer wall of the reaction chamber at each position is almost consistent, the inner barrel is arranged at the central position of the inner cavity of the outer barrel through the coaxial arrangement of the inner barrel and the outer barrel, so that the tail gas flowing at each position can be equally and efficiently treated, and meanwhile, the resource of the SCR converter is not wasted.

Further, the air inlet pipe is arranged at the end part of the left side of the outer barrel, and the air outlet pipe is arranged at the upper part of the left side of the outer barrel and is perpendicular to the air inlet pipe. Because the system is arranged below the frame of the non-road mobile machine, the convenience in actual installation is ensured by limiting the specific positions of the air inlet pipe and the air outlet pipe.

According to the technical scheme, the invention integrates the functions of DOC, DPF and SCR, the SCR converter is wrapped on the surfaces of the DOC converter and the DPF filter, the structure is compact, the total volume and the linear length of the DOC + DPF + SCR system can be effectively reduced, the total volume is only about 1.2 times of that of the original silencer, the removal efficiency of PM and PN reaches more than 95%, the conversion efficiency of NOx reaches more than 85%, the system can be installed on non-road mobile machinery without changing the structure of a vehicle, and the installation and the arrangement are convenient, and compared with the prior art, the invention has the following advantages:

1. the SCR converter is wrapped on the surface of the reaction chamber in which the DOC converter and the DPF filter are arranged, so that the linear length of the system is effectively reduced;

2. the invention integrates the functions of DOC, DPF and SCR, SCR treatment is the final purification process of the tail gas of the system, and the SCR converter is selected to be wrapped outside the reaction chamber, and we can find that the SCR converter in the outer ring only needs to occupy a small diameter to obtain a large volume, thereby realizing the efficiency matched with the treatment of the DOC converter and the DPF in front, effectively reducing the diameter of the system and reducing the volume of the system;

3. the mixing cavity with the small air dispersing holes uniformly distributed on the surface is arranged, and the urea nozzle is arranged right opposite to the center of the mixing cavity, so that NOx in tail gas and urea spray are fully mixed in the mixing cavity, urea crystallization can be prevented, and the NOx conversion efficiency of the follow-up SCR converter in tail gas treatment is greatly improved;

4. the gas pipe is arranged around the outer side of the mixing cavity, tail gas is conveyed rightwards through the gas pipe, then turns around leftwards and returns to enter the mixing cavity, and the mixing cavity and the gas pipe are arranged in the same space, so that the linear length of the system is further effectively reduced;

5. the urea spraying device is also provided with a first partition plate and a second partition plate, the first partition plate, the second partition plate and the edge section form a narrow closed space, tail gas is sprayed outwards at high speed through the inclined gas nozzles on the second partition plate, and the tail gas forms vortex rotating in the same direction due to the fact that all the inclined gas nozzles are arranged in the clockwise direction or the anticlockwise direction, so that the tail gas and urea spray are mixed more fully.

Drawings

The present invention will be described in further detail with reference to the following detailed description and accompanying drawings.

FIG. 1 is a schematic structural diagram according to a first embodiment;

FIG. 2 is a schematic structural diagram of the second embodiment;

FIG. 3 is a schematic structural diagram according to a third embodiment;

FIG. 4 is an exploded view of a portion of FIG. 3;

FIG. 5 is a schematic view of the second separator plate of FIG. 3;

wherein, 1, an outer cylinder; 2. an inner barrel; 21. a reaction chamber; 22. a mixing chamber; 221. a main body section; 2211. air diffusing holes; 222. an edge segment; 23. a DOC converter; 24. a DPF filter; 25. a contraction section; 251. a second air outlet; 3. an air inlet pipe; 31. a circular pipe section; 32. an expansion section; 4. an air outlet pipe; 5. a gas delivery pipe; 6. a urea nozzle; 7. a first separator; 71. a first fixing hole; 72. a first air outlet hole; 8. an SCR converter; 9. a second separator; 91. a second fixing hole; 92. a third air outlet; 93. a flow deflector; 10. a plug; 11. and (4) threading.

Detailed Description

In order to make the objects, technical solutions and advantages of the present embodiments more clear, the technical solutions in the present embodiments will be clearly and completely described below with reference to the drawings in the present embodiments, and it is obvious that the described embodiments are some, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the scope of the present protection.

In the description of the present invention, it is to be understood that the terms "upper end", "lower end", "tail end", "left side", "right side", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience of description and simplicity of description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit to a number of indicated technical features. Thus, features defined as "first," "second," "third," etc. may explicitly or implicitly include one or more of the features.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integral; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

Example one

As shown in fig. 1 and 4, a compact exhaust gas post-treatment system comprises an outer cylinder 1, an inner cylinder 2, an air inlet pipe 3, an air outlet pipe 4, an air delivery pipe 5 and a urea nozzle 6, wherein the left side and the right side of the outer cylinder 1 are closed, the air inlet pipe 3 and the air outlet pipe 4 are installed on the left side of the outer cylinder, the urea nozzle 6 is installed on the right side of the outer cylinder, the air inlet pipe 3 has an air inlet guiding function, the air outlet pipe 4 has an air outlet guiding function, and the urea nozzle 6 is used for delivering urea and atomizing the urea; the inner cylinder 2 is arranged in a cavity of the outer cylinder 1 and comprises a reaction chamber 21 and a mixing cavity 22, the left end of the reaction chamber 21 is connected with the tail end of the air inlet pipe 3, the shape of the reaction chamber 21 is not limited, the reaction chamber is shown by a hollow circular pipe in the embodiment, a DOC converter 23 and a DPF filter 24 are arranged in the inner cavity of the reaction chamber from left to right, an oxidation type catalyst is arranged in the DOC converter 23, and the DOC converter 23 can oxidize CO, HC and soluble organic matters SOF in particulate matters through the action of the catalyst to generate harmless CO2 and H2O; meanwhile, part of NO in the tail gas is oxidized to generate NO2 for the regeneration of the rear-stage DPF filter 24, and the DPF filter 24 mainly filters and stores the soot particles in the tail gas; the mixing cavity 22 comprises a main body section 221, the main body section 221 is uniformly distributed with tiny air diffusing holes 2211, the left side of the main body section 221 is connected with the reaction chamber 21, the joint of the left side and the right side of the main body section 221 is closed, the right side of the main body section is open and is fixed through a first partition plate 7, the first partition plate 7 is fixed in the cavity of the outer barrel 1, a certain space is reserved between the first partition plate 7 and the right side end of the outer barrel 1, a first fixing hole 71 for the right side of the main body section 221 to pass through and fix is arranged on the first partition plate 7, a plurality of air conveying pipes 5 are arranged around the outer side of the main body section 221, wherein the number of the air conveying pipes 5 is generally limited to 5 to 12, the left end of the air conveying pipe 5 is communicated with the reaction chamber 21, the right end of the air conveying pipe is fixed in a first air outlet hole 72 correspondingly arranged on the first partition plate 7, an SCR converter 8 for wrapping the reaction chamber 21 is arranged around the inner wall of the outer barrel 1 and the outer wall of the reaction chamber 21, a selective reduction catalyst is arranged in the SCR converter 8, after mixing NOx with urea, NOx is converted to nitrogen and water by the action of a catalyst.

The flow direction of tail gas through the system is as follows: enters from the air inlet pipe 3, passes through the DOC converter 23 and the DPF filter 24 in the reaction chamber 21 rightwards, then passes through the air delivery pipe 5 rightwards to be mixed with urea spray sprayed from the urea nozzle 6, then returns leftwards to enter the mixing cavity 22 to be fully mixed and dispersed through the air dispersion holes 2211, and finally continuously passes through the SCR converter 8 leftwards and is discharged through the air outlet pipe 4 along the space between the inner wall of the outer barrel 1 and the outer wall of the reaction chamber 21.

In the present embodiment, the outer cylinder 1 and the inner cylinder 2 in fig. 1 are illustrated as cylinders, but may have other shapes such as square cylinders; the pipe diameter of the mixing chamber 22 is smaller than that of the reaction chamber 21 as seen in fig. 1, but the pipe diameter of the mixing chamber 22 is not limited to be larger or smaller than that of the reaction chamber 21, and the pipe diameter of the mixing chamber 22 may be equal to or larger than that of the reaction chamber 21, so the shape of the gas pipe 5 is not limited to a straight pipe, and may be an elbow pipe.

Example two

As shown in fig. 2 and 4, a compact exhaust gas post-treatment system comprises an outer cylinder 1, an inner cylinder 2, an air inlet pipe 3, an air outlet pipe 4, an air delivery pipe 5 and a urea nozzle 6, wherein the left side and the right side of the outer cylinder 1 are closed, the air inlet pipe 3 and the air outlet pipe 4 are installed on the left side of the outer cylinder, the urea nozzle 6 is installed on the right side of the outer cylinder, the air inlet pipe 3 has an air inlet guiding function, the air outlet pipe 4 has an air outlet guiding function, and the urea nozzle 6 is used for delivering urea and atomizing the urea; the inner cylinder 2 is arranged in a cavity of the outer cylinder 1 and comprises a reaction chamber 21 and a mixing cavity 22, the left end of the reaction chamber 21 is connected with the tail end of the air inlet pipe 3, the shape of the reaction chamber 21 is not limited, the reaction chamber is shown by a hollow circular pipe in the embodiment, a DOC converter 23 and a DPF filter 24 are arranged in the inner cavity of the reaction chamber from left to right, an oxidation type catalyst is arranged in the DOC converter 23, and the DOC converter 23 can oxidize CO, HC and soluble organic matters SOF in particulate matters through the action of the catalyst to generate harmless CO2 and H2O; meanwhile, part of NO in the tail gas is oxidized to generate NO2 for the regeneration of the rear-stage DPF filter 24, and the DPF filter 24 mainly filters and stores the soot particles in the tail gas; the mixing cavity 22 comprises a main body section 221, the main body section 221 is uniformly distributed with tiny air diffusing holes 2211, the left side of the main body section 221 is connected with the reaction chamber 21, the joint of the left side and the right side of the main body section 221 is closed, the right side of the main body section is open and is fixed through a first partition plate 7, the first partition plate 7 is fixed in the cavity of the outer barrel 1, a certain space is reserved between the first partition plate 7 and the right side end of the outer barrel 1, a first fixing hole 71 for the right side of the main body section 221 to pass through and fix is arranged on the first partition plate 7, a plurality of air conveying pipes 5 are arranged around the outer side of the main body section 221, wherein the number of the air conveying pipes 5 is generally limited to 5 to 12, the left end of the air conveying pipe 5 is communicated with the reaction chamber 21, the right end of the air conveying pipe is fixed in a first air outlet hole 72 correspondingly arranged on the first partition plate 7, an SCR converter 8 for wrapping the reaction chamber 21 is arranged around the inner wall of the outer barrel 1 and the outer wall of the reaction chamber 21, a selective reduction catalyst is arranged in the SCR converter 8, after mixing NOx with urea, NOx is converted to nitrogen and water by the action of a catalyst.

Be equipped with a shrinkage section 25 between reaction chamber 21 and the hybrid chamber 22, shrinkage section 25 reduces from a left side to right bore gradually, and one side that its bore is big is connected with reaction chamber 21, the opposite side is connected with hybrid chamber 22, reaction chamber 21, hybrid chamber 22 are hollow tube and coaxial setting, shrinkage section 25 is equipped with the second venthole 251 that quantity corresponds to 5 numbers of gas-supply pipes on its slope lateral wall. The inner cylinder 2 and the outer cylinder 1 are coaxially arranged, a space is reserved between the inner cylinder and the inner wall of the outer cylinder 1, and the urea nozzle 6 is arranged on the right side of the outer cylinder 1 and faces the center of the mixing cavity 22.

The air inlet pipe 3 is funnel-shaped and comprises a horizontal circular pipe section 31 and an expansion section 32, the caliber of the expansion section 32 is gradually increased from left to right, and one side with the large caliber is connected with the reaction chamber 21.

EXAMPLE III

As shown in fig. 3, a compact exhaust gas post-treatment system comprises an outer cylinder 1, an inner cylinder 2, an air inlet pipe 3, an air outlet pipe 4, an air delivery pipe 5 and a urea nozzle 6, wherein the left side and the right side of the outer cylinder 1 are closed, the air inlet pipe 3 and the air outlet pipe 4 are installed on the left side of the outer cylinder 1, the urea nozzle 6 is installed on the right side of the outer cylinder, the air inlet pipe 3 has an air inlet guiding function, the air outlet pipe 4 has an air outlet guiding function, the urea nozzle 6 is used for conveying urea and atomizing the urea, the air inlet pipe 3 is arranged at the end part of the left side of the outer cylinder 1, and the air outlet pipe 4 is arranged at the upper part of the left side of the outer cylinder 1 and is perpendicular to the air inlet pipe 3; the inner cylinder 2 is arranged in a cavity of the outer cylinder 1 and comprises a reaction chamber 21 and a mixing cavity 22, the air inlet pipe 3 is funnel-shaped and comprises a horizontal circular pipe section 31 and an expansion section 32, the caliber of the expansion section 32 is gradually increased from left to right, one side with the larger caliber is connected with the reaction chamber 21, the shape of the reaction chamber 21 is not limited, the expansion section 32 is illustrated by a hollow circular pipe in the embodiment, a DOC converter 23 and a DPF filter 24 are arranged in an inner cavity of the expansion section from left to right, an oxidation type catalyst is arranged in the DOC converter 23, and the DOC converter 23 can oxidize CO, HC and soluble organic matters SOF in particulate matters through the action of the catalyst to generate harmless CO2 and H2O; meanwhile, part of NO in the exhaust gas is oxidized to generate NO2 for the regeneration of the later stage DPF filter 24, and the DPF filter 24 mainly filters and stores the soot particles in the exhaust gas. An SCR converter 8 for wrapping the reaction chamber 21 is arranged between the inner wall of the outer barrel 1 and the outer wall of the reaction chamber 21 in a surrounding mode, a selective reduction catalyst is arranged in the SCR converter 8, and NOx is converted into nitrogen and water under the action of the catalyst after being mixed with urea.

As shown in fig. 4, the mixing chamber 22 includes a main body section 221 and an edge section 222, the main body section 221 is uniformly distributed with tiny air diffusing holes 2211, the left side of the main body section 221 is connected with the reaction chamber 21, the connection position of the left side and the right side of the main body section 221 is closed, the right side of the main body section 221 is open and fixed by a first partition plate 7, the first partition plate 7 is fixed in the cavity of the outer cylinder 1, a certain space is left between the first partition plate 7 and the right side end of the outer cylinder 1, the first partition plate 7 is provided with a first fixing hole 71 for the right side of the main body section 221 to pass through and fix, the outer side of the main body section 221 is surrounded by a plurality of air pipes 5, wherein the number of the air pipes 5 is generally limited to 5 to 12, in this embodiment, 6 air pipes are provided, the left end of the air pipes 5 is communicated with the reaction chamber 21, the right end is fixed in the first air outlet hole 72 correspondingly provided on the first partition plate 7, the left side of the edge section 222 is connected with the main body section 221, the edge section 222 is a hollow tube with a certain length, as shown in fig. 5, the right side of the edge section 222 is fixed by a second partition plate 9, a second fixing hole 91 for the right side of the edge section 222 to pass through and fix is arranged on the second partition plate 9, a plurality of third air outlets 92 are arranged around the second fixing hole 91, and the number of the third air outlets 92 is greater than that of the first air outlets 72; each third air outlet 92 is provided with a flow deflector 93, the flow deflector 93 is an upwelled spherical cover plate, the flow deflector 93 and the third air outlet 92 jointly form an oblique air jet for obliquely jetting the tail gas, and all the oblique air jets are arranged along the clockwise direction.

Be equipped with a shrinkage section 25 between reaction chamber 21 and the hybrid chamber 22, shrinkage section 25 reduces from a left side to right bore gradually, and one side that its bore is big is connected with reaction chamber 21, the opposite side is connected with hybrid chamber 22, reaction chamber 21, hybrid chamber 22 are hollow tube and coaxial setting, shrinkage section 25 is equipped with the second venthole 251 that quantity corresponds to 5 numbers of gas-supply pipes on its slope lateral wall. The inner cylinder 2 and the outer cylinder 1 are coaxially arranged, a space is reserved between the inner cylinder and the inner wall of the outer cylinder 1, and the urea nozzle 6 is arranged on the right side of the outer cylinder 1 and faces the center of the mixing cavity 22. The contraction section 25, the main body section 221 and the edge section 222 are of a funnel-shaped integrated structure, and a plug 10 is arranged at the connection position of the contraction section 25 and the main body section 221 for plugging. The expansion section 32, the contraction section 25 and the reaction chamber 21 are respectively in threaded connection, the expansion section 32 and the contraction section 25 are provided with threads 11 at the connection part with the reaction chamber 21, the reaction chamber 21 is correspondingly provided with internal threads (not shown), and in addition, other detachable connection modes such as buckling, sleeving and the like can be adopted for the expansion section 32, the contraction section 25 and the reaction chamber 21.

The above description is provided by way of example only to aid understanding of the present invention, and is not intended to limit the present invention. For a person skilled in the art, several simple deductions, modifications or substitutions may be made according to the present idea.

Claims

1. The compact type tail gas aftertreatment system is characterized by comprising an outer cylinder (1), an inner cylinder (2), an air inlet pipe (3), an air outlet pipe (4), an air delivery pipe (5) and a urea nozzle (6), wherein the left side and the right side of the outer cylinder (1) are closed, the left side of the outer cylinder is provided with the air inlet pipe (3) and the air outlet pipe (4), and the right side of the outer cylinder is provided with the urea nozzle (6); the inner cylinder (2) is arranged in a cavity of the outer cylinder (1) and comprises a reaction chamber (21) and a mixing cavity (22), the left end of the reaction chamber (21) is connected with the tail end of the air inlet pipe (3), and a DOC converter (23) and a DPF filter (24) are arranged in the inner cavity of the reaction chamber from left to right; the mixing cavity (22) comprises a main body section (221), wherein tiny air diffusing holes (2211) are uniformly distributed in the main body section (221), the left side of the main body section (221) is connected with the reaction chamber (21), the joint of the main body section and the reaction chamber is closed, the right side of the main body section (221) is open and is fixed through a first partition plate (7), a first fixing hole (71) for allowing the right side of the main body section (221) to penetrate and fix is formed in the first partition plate (7), a plurality of air conveying pipes (5) are arranged around the outer side of the main body section (221), the left end of each air conveying pipe (5) is communicated with the reaction chamber (21), the right end of each air conveying pipe is fixed in a first air outlet hole (72) correspondingly formed in the first partition plate (7), and an SCR converter (8) wrapping the reaction chamber (21) is arranged between the inner wall of the outer barrel (1) and the outer wall of the reaction chamber (21); the flow direction of tail gas through the system is as follows: enters from an air inlet pipe (3), passes through a DOC converter (23) and a DPF filter (24) in a reaction chamber (21) rightwards, then passes through an air conveying pipe (5) rightwards to be mixed with urea spray sprayed from a urea nozzle (6), then returns leftwards to enter a mixing cavity (22) to be fully mixed and dispersed through a dispersion hole (2211), and finally is attached to a space between the inner wall of an outer barrel (1) and the outer wall of the reaction chamber (21) to continuously pass through an SCR converter (8) leftwards and be discharged through an air outlet pipe (4);

a contraction section (25) is further arranged between the reaction chamber (21) and the mixing cavity (22), the caliber of the contraction section (25) is gradually reduced from left to right, the side with the large caliber of the contraction section is connected with the reaction chamber (21), and the inclined side wall of the contraction section (25) is provided with second air outlet holes (251) the number of which corresponds to the number of the air conveying pipes (5);

the mixing cavity (22) further comprises an edge section (222), the left side of the edge section (222) is connected with the main body section (221), the edge section (222) is a hollow pipe with a certain length, the right side of the edge section (222) is fixed through a second partition plate (9), a second fixing hole (91) for allowing the right side of the edge section (222) to pass through and be fixed is formed in the second partition plate (9), a plurality of third air outlets (92) are formed in the periphery of the second fixing hole (91) in a surrounding mode, and the number of the third air outlets (92) is greater than that of the first air outlets (72).

2. The compact exhaust gas aftertreatment system according to claim 1, wherein the reaction chamber (21) and the mixing chamber (22) are hollow tubes, the tube diameter of the mixing chamber (22) is smaller than that of the reaction chamber (21), and the reaction chamber (21) and the mixing chamber (22) are coaxially arranged.

3. The compact exhaust gas aftertreatment system according to claim 1, wherein each of the third outlet holes (92) is further provided with a baffle (93), the baffle (93) is an upwardly arched spherical cover plate, the baffle (93) and the third outlet holes (92) together form an oblique gas nozzle for obliquely ejecting exhaust gas, and all the oblique gas nozzles are arranged along a clockwise direction or an anticlockwise direction.

4. The compact exhaust gas aftertreatment system according to claim 1, wherein the constriction section (25), the main section (221) and the edge section (222) are funnel-shaped and integrated, and a plug (10) is provided at the connection between the constriction section (25) and the main section (221) for plugging.

5. A compact exhaust gas aftertreatment system according to claim 1 or 4, wherein the inlet pipe (3) is funnel-shaped and comprises a horizontal circular pipe section (31) and an expansion section (32), the diameter of the expansion section (32) increases gradually from left to right, and the side with the larger diameter is connected with the reaction chamber (21).

6. A compact exhaust gas aftertreatment system according to claim 5, wherein the expansion section (32), the contraction section (25) and the reaction chamber (21) are each detachably screwed.

7. A compact exhaust gas aftertreatment system according to claim 1, 2 or 6, characterized in that the inner cylinder (2) is arranged coaxially with the outer cylinder (1), leaving a space between it and the inner wall of the outer cylinder (1), and the urea nozzle (6) is arranged right on the outer cylinder (1) opposite the centre of the mixing chamber (22).

8. A compact exhaust gas aftertreatment system according to claim 7, wherein the inlet duct (3) is arranged at the left end of the outer cylinder (1), and the outlet duct (4) is arranged at the upper left side of the outer cylinder (1) and perpendicular to the inlet duct (3).