Catalytic silencer
By setting up connection pipes, drainage baffles and porous pipes in the mixing chamber of the catalytic muffler, the problem of uneven urea distribution and difficulty in meeting the European Five standards in the prior art is solved, and uniform mixing and efficient waste gas and urea are achieved Catalytic reaction reduces NOx emissions.
Patent Information
- Application Number
- CN202420643227.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-29
- Publication Date
- 2025-02-14
- Estimated Expiration
- 2034-03-29
AI Technical Summary
Existing catalytic mufflers have shortcomings in reducing NOx emissions, especially when meeting the requirements of the NOx value of Euro V emission regulations is less than 0.4g/km*h, it is difficult to achieve uniform distribution and efficient conversion through traditional mixed chamber urea injection technology. .
The connecting tube, drainage baffle and porous tube are arranged in the mixing chamber of the catalytic muffler. These structures promote the uniform mixing of urea and exhaust gas and improve the efficiency of the catalytic reaction.
By setting up a connecting pipe, drainage baffle and porous pipe in the mixing chamber, the mixing uniformity between waste gas and urea is significantly improved, the efficiency of catalytic reaction is improved, the emission of NOx is reduced, and the requirements of the Euro V emission regulations can be met. .
Smart Images
Figure CN222478795U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to a post-processing technology, and more specifically, to a catalytic muffler. Background Art
[0002] The most critical equipment in post-treatment technology is the catalytic muffler. The exhaust gas of the engine enters from the exhaust inlet pipe of the catalytic muffler and produces a redox reaction under the catalysis of the catalyst to achieve the purpose of catalytic conversion of the exhaust gas. The unconverted exhaust gas is discharged to the outside from the exhaust outlet pipe of the catalytic muffler.
[0003] At present, the SCR front and rear stages of the K08 platform, which is common to car machines, are 4+5-inch carriers, of which 2 inches of the rear SCR are ASC. However, the catalytic muffler structure is mainly designed to meet the emission regulations of non-road T4. However, the NOx value of the emission regulations of non-road T4 must be lower than 2g / km*h, and the NOx value of the emission regulations of Euro V must be lower than 0.4g / km*h. Therefore, how to reduce the NOx value is a current technical bottleneck in this field. The prior art is to add a urea injector before the SCR of the catalytic muffler, and to achieve the purpose of reducing NOx emissions by mixing urea with the exhaust gas in the catalytic muffler. However, in the traditional mixing chamber, urea is directly injected into the mixing chamber to mix with the exhaust gas. Since the flow rate of the exhaust gas in the catalytic muffler is relatively fast, and the injection direction of urea is perpendicular to the flow direction of the exhaust gas, this results in a lower amount of urea obtained in part of the exhaust gas away from the urea injector, resulting in uneven urea distribution, making it difficult for NOx emissions to meet the emission standards of Euro V. Utility Model Content
[0004] The technical problem to be solved by the utility model is to provide a catalytic muffler for the deficiencies of the prior art, which effectively improves the conversion efficiency and reduces the emission of NOx.
[0005] A catalytic muffler described in the utility model comprises a shell, one side of the shell is provided with an air inlet, the other side of the shell is provided with an air outlet, a DOC carrier, a DPF carrier, a front-stage SCR carrier and a rear-stage SCR carrier are sequentially installed in the shell between the air inlet and the air outlet; a mixing chamber is provided in the shell between the DPF carrier and the front-stage SCR carrier, a connecting pipe is provided in the mixing chamber, the connecting pipe is connected to a urea injector installed above the mixing chamber, a drainage baffle is installed below the connecting pipe, the drainage baffle is close to the DPF carrier, a drainage channel connected to the connecting pipe is provided between the drainage baffle, the connecting pipe and the DPF carrier, a porous pipe connected to the connecting pipe is installed below the connecting pipe, and the porous pipe is close to the front-stage SCR carrier.
[0006] As a further improvement, the connecting pipe is arranged obliquely in the mixing chamber.
[0007] As a further improvement, a perforated plate is provided between the porous tube and the front-stage SCR carrier, and the connecting tube is inclined toward the perforated plate.
[0008] As a further improvement, an isolation plate is installed in the shell between the air inlet and the DOC carrier, and the isolation plate is divided into an upper plate body and a lower plate body. The upper plate body is provided with a plurality of through holes arranged in an array, and the lower plate body is provided with a plurality of columns of through holes 2, and the through holes 2 in two adjacent columns are staggered in the upper and lower directions.
[0009] Furthermore, the diameter of the through hole one is smaller than the diameter of the through hole two.
[0010] Furthermore, the isolation plate has an arc-shaped structure.
[0011] As a further improvement, a heat insulation cover is provided on the periphery of the shell, and heat insulation cotton is provided between the heat insulation cover and the shell.
[0012] As a further improvement, the volume ratio of the DOC carrier is 0.8; the volume ratios of the two-stage SCR carriers are both 1.8.
[0013] As a further improvement, the lengths of the front-stage SCR carrier and the rear-stage SCR carrier are both 5 inches; wherein 2 inches of the rear-stage SCR carrier are ASC.
[0014] Beneficial Effects
[0015] The utility model has the advantages that a connecting pipe, a drainage baffle and a porous pipe are arranged in the mixing chamber, so that urea and exhaust gas are mixed in the connecting pipe and then discharged from the porous pipe, which can promote the mixing uniformity between the exhaust gas and urea, thereby improving the efficiency of the catalytic reaction and reducing the emission of NOx. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a front view schematic diagram of the catalytic muffler of the utility model;
[0017] Figure 2 It is a side schematic diagram of the catalytic muffler of the utility model;
[0018] Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure at AA in the middle;
[0019] Figure 4 It is a schematic diagram of the internal installation structure of the mixing chamber of the utility model.
[0020] Among them: 1-heat insulation cover, 2-shell, 3-air inlet, 4-air outlet, 5-, 6-DOC carrier, 7-DOC carrier, 8-mixing chamber, 9-front stage SCR carrier, 10-rear stage SCR carrier, 11-urea injector, 12-connecting pipe, 13-drainage baffle, 14-porous pipe, 15-orifice plate, 51-upper plate body, 52-lower plate body, 53-through hole one, 54-through hole two. DETAILED DESCRIPTION
[0021] The utility model is further described below in conjunction with the embodiments, but does not constitute any limitation to the utility model. Any limited modifications made by anyone within the scope of the claims of the utility model are still within the scope of the claims of the utility model.
[0022] See also Figure 1-Figure 4 The utility model is a catalytic muffler, comprising a shell 2. An air inlet 3 is provided on one side of the shell 2, and an air outlet 4 is provided on the other side of the shell 2. A DOC carrier 6, a DPF carrier 7, a front-stage SCR carrier 9 and a rear-stage SCR carrier 10 are sequentially installed in the shell 2 between the air inlet 3 and the air outlet 4. Among them, the materials of the DOC carrier 6, the DPF carrier 7, the front-stage SCR carrier 9 and the rear-stage SCR carrier 10 can all be made of ceramics, cordierite, full-stage precious metal catalysts, etc. For details, please refer to the existing manufacturing process. The utility model does not improve its specific material formula and manufacturing process. A heat insulation cover 1 is provided on the periphery of the shell 2, and a 12mm thick heat insulation cotton is provided between the heat insulation cover 1 and the shell 2.
[0023] In actual application, compared with the carrier matching of the K08 platform used in the car machine, the A08 in this embodiment that complies with Euro V is matched with an engine of 180KW-280KW, and its catalytic muffler uses a carrier similar to that of the car machine, and the DOC carrier 6 and DPF carrier 7 use the carrier of the K09 platform of the car machine. The length of the front-stage SCR carrier 9 and the rear-stage SCR carrier 10 is 5+5 inches, of which 2 inches of the rear-stage SCR carrier 10 is the ASC carrier. The main reason for this design is that the exhaust flow and exhaust temperature of the engine that complies with Euro V require larger specifications of DOC and DPF than the K08 of the car machine in order to oxidize, capture and filter the carbon monoxide and hydrocarbons, particulate matter, etc. in the diesel engine exhaust gas to meet the emission requirements of Euro V; in addition, compared with the SCR front and rear stages of the K08 commonly used in car machines, the SCR carrier of this catalytic muffler has one more inch to be able to more fully filter and absorb ammonia nitrogen and prevent ammonia leakage. After all, Euro V emission regulations are stricter than non-road T4 emission regulations. The NOx value of non-road T4 emission regulations must be lower than 2g / km*h, and the NOx value of Euro V emission regulations must be lower than 0.4g / km*h.
[0024] This embodiment adopts the design of DOC carrier 6, SCR carrier and ASC carrier, which is conducive to reducing back pressure and improving conversion efficiency. In actual application, the smaller the carrier wall thickness, the smaller the exhaust back pressure caused by the carrier itself, and the better the engine performance. Therefore, the larger the mesh number of the carrier, the thinner the carrier wall, which is conducive to increasing the circulation of gas, while reducing the volume of the carrier and reducing the back pressure of the carrier. Under the same exhaust volume, the more mesh number and the smaller the carrier wall thickness, the higher the catalytic conversion efficiency of the carrier; under the same mesh number conditions, the smaller the wall thickness of the carrier, the higher the catalytic conversion efficiency.
[0025] In addition, the volume ratio of the DOC substrate 6 of the catalytic muffler is 0.8, and the volume ratio of the two-stage SCR substrate is 1.8. This volume ratio complies with the Q / YCCD 2523-2022 non-road after-treatment catalytic unit selection specification.
[0026] An isolation plate 5 is installed in the shell 2 between the air inlet 3 and the DOC carrier 6. The isolation plate 5 is in an arc-shaped structure, and its concave surface faces the DOC carrier 6. The isolation plate 5 is divided into an upper plate body 51 and a lower plate body 52. The upper plate body 51 is provided with a plurality of through holes 1 53 arranged in an array, and the lower plate body 52 is provided with a plurality of rows of through holes 2 54, each row is composed of a plurality of through holes, and the two adjacent rows of through holes 2 54 are arranged in an up-down staggered manner, and the diameter of the through hole 1 53 is smaller than the diameter of the through hole 2 54. Since the air inlet 3 is perpendicular to the inner cavity of the shell 2, such a setting can improve the uniformity of other gases entering the shell 2.
[0027] A mixing chamber 8 is provided in the shell 2 between the DPF carrier 7 and the front-stage SCR carrier 9. A connecting pipe 12 is provided in the mixing chamber 8. The connecting pipe 12 is connected to the urea injector 11 installed on the shell 2. A drainage baffle 13 is installed below the connecting pipe 12. The drainage baffle 13 is close to the DPF carrier 7. A drainage channel connected to the connecting pipe 12 is provided between the drainage baffle 13, the connecting pipe 12 and the DPF carrier. A porous tube 14 connected to the connecting pipe 12 is installed below the connecting pipe 12. Among them, the porous tube 14 is a tube with a plurality of through holes on the tube wall. The porous tube 14 is close to the front-stage SCR carrier 9. A perforated plate 15 is provided between the porous tube 14 and the front-stage SCR carrier 9. Among them, the perforated plate 15 is a plate with a plurality of through holes. Such a design can promote the mixing between the exhaust gas and urea to improve the efficiency of the catalytic reaction. Specifically, the functions of the mixer may include the following aspects:
[0028] First, uniform mixing. The exhaust gas and urea are guided and mixed by the connecting pipe 12 and the porous pipe 14, so that the exhaust gas is more evenly mixed with urea before entering the SCR carrier, ensuring that the urea can fully contact the pollutants in the exhaust gas and improve the effect of catalytic conversion.
[0029] Second, increase the contact area. The design of the mixing chamber 8 can increase the contact area between the exhaust gas and urea, thereby improving the reaction rate and conversion rate.
[0030] Third, optimize the air flow distribution. The porous tube 14 and the perforated plate 15 can help the exhaust gas flow more evenly in the catalytic muffler, avoid air flow dead corners or local high-speed air flow, and thus improve the overall performance of the catalytic muffler.
[0031] Fourth, reduce the temperature gradient. The mixing chamber 8 can promote the exhaust gas to flow evenly through the catalytic muffler, reduce the temperature gradient, and help maintain the activity and stability of the catalyst.
[0032] In this embodiment, the connecting pipe 12 is arranged obliquely in the mixing chamber 8, and the connecting pipe 12 is inclined toward the orifice plate 15, which is conducive to the input of exhaust gas into the SCR carrier. The total length of the mixing chamber 8 is 350 mm; the diameter of the connecting pipe 12 is 140 mm.
[0033] The following table shows the test results of the catalytic muffler of the present invention on the standard NRSC.
[0034]
[0035] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent.
Claims
1. A catalytic muffler, characterized in that: The invention comprises a shell (2), wherein one side of the shell (2) is provided with an air inlet (3), and the other side of the shell (2) is provided with an air outlet (4); a DOC carrier (6), a DPF carrier (7), a front-stage SCR carrier (9) and a rear-stage SCR carrier (10) are sequentially installed in the shell (2) between the air inlet (3) and the air outlet (4); a mixing chamber (8) is provided in the shell (2) between the DPF carrier (7) and the front-stage SCR carrier (9), and a connecting pipe (12) is provided in the mixing chamber (8); The connecting pipe (12) is connected to a urea injector (11) installed above the mixing chamber (8); a drainage baffle (13) is installed below the connecting pipe (12); the drainage baffle (13) is close to the DPF carrier (7); a drainage channel connected to the connecting pipe (12) is provided between the drainage baffle (13), the connecting pipe (12) and the DPF carrier; a porous pipe (14) connected to the connecting pipe (12) is installed below the connecting pipe (12); the porous pipe (14) is close to the front-stage SCR carrier (9).
2. A catalytic muffler according to claim 1, characterized in that: The connecting pipe (12) is arranged obliquely in the mixing chamber (8).
3. A catalytic muffler according to claim 1, characterized in that: A perforated plate (15) is provided between the porous tube (14) and the front-stage SCR carrier (9), and the connecting tube (12) is inclined toward the perforated plate (15).
4. A catalytic muffler according to claim 1, characterized in that: An isolation plate (5) is installed in the shell (2) between the air inlet (3) and the DOC carrier (6), and the isolation plate (5) is divided into an upper plate body (51) and a lower plate body (52). The upper plate body (51) is provided with a plurality of through holes (53) arranged in an array, and the lower plate body (52) is provided with a plurality of rows of through holes (54), and two adjacent rows of through holes (54) are arranged in an up-and-down staggered manner.
5. A catalytic muffler according to claim 4, characterized in that: The diameter of the through hole one (53) is smaller than the diameter of the through hole two (54).
6. A catalytic muffler according to claim 4, characterized in that: The isolation plate (5) is in an arc-shaped structure.
7. A catalytic muffler according to claim 1, characterized in that: A heat insulation cover (1) is provided on the periphery of the shell (2), and heat insulation cotton is provided between the heat insulation cover (1) and the shell (2).
8. A catalytic muffler according to claim 1, characterized in that: The volume ratio of the DOC carrier (6) is 0.8; the volume ratios of the two-stage SCR carriers are both 1.
8.
9. A catalytic muffler according to claim 1, characterized in that: The lengths of the front-stage SCR carrier (9) and the rear-stage SCR carrier (10) are both 5 inches; wherein 2 inches of the rear-stage SCR carrier (10) are ASC.