Adblue aqueous solution filling and decomposing device

Abstract

The invention belongs to the technical field of diesel engine selective catalytic reduction, and particularly relates to an automotive urea water solution filling and decomposing device which comprises a mixer, a urea pump, a flowing pipeline and a capillary structure. The mixer is provided with a capillary structure, a two-way pipeline and a diffusion pipeline are arranged in the mixer, and the aperture of the two-way pipeline is larger than that of the diffusion pipeline. When the SCR system runs, a urea pump injects a urea water solution into the two-way pipeline, the pipeline is filled with the urea water solution under pressure driving, and the urea water solution flows into the diffusion pipeline under the dual action of pressure and capillary action, permeates to the surface of the mixer through the capillary structure of the mixer and makes contact with high-temperature waste gas to be evaporated and decomposed. By means of the arrangement of the capillary structure and the flow field, uniform distribution of ammonia gas is achieved, evaporation and decomposition of a urea water solution are accelerated, generation of urea decomposition by-products is restrained, deposition high-risk areas near a traditional nozzle are reduced, the conversion efficiency of an SCR system is improved, and good market application prospects are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of diesel engine selective catalytic reduction, and particularly relates to a device for filling and decomposing an aqueous urea solution for vehicles. Background Art

[0002] With the continuous tightening of emission regulations, in order to solve the problem of nitrogen oxide emissions, selective catalytic reduction technology has been widely applied to diesel engines. The principle of this technology is to reduce nitrogen oxides to environmentally harmless nitrogen and water by using ammonia in the catalytic converter. Considering that ammonia has a pungent smell and is corrosive, an aqueous urea solution with a mass fraction of 32.5% is actually used. The aqueous urea solution is sprayed into the aftertreatment system, and after undergoing pyrolysis and hydrolysis, ammonia gas is obtained to achieve the purpose of eliminating nitrogen oxides.

[0003] In the SCR system, the aqueous urea solution is usually filled into the tail gas aftertreatment system through a nozzle. The spray droplets collide, evaporate, and decompose to generate ammonia gas, which participates in the selective catalytic reduction reaction of the SCR system. The accurate control and uniform distribution of the ammonia gas amount directly affect the efficiency and service life of the SCR system. In practice, due to the limitations of the evaporation rate and reaction rate, part of the aqueous urea solution is not completely converted into ammonia gas, but undergoes side reactions with the participation of intermediate products to form solid deposits. The deposits are mainly distributed in the nozzle, nozzle base, mixer, and exhaust pipe. The presence of the deposits affects the conversion efficiency of the SCR system on the one hand and the airflow movement in the exhaust system on the other hand, resulting in an increase in back pressure.

[0004] The information disclosed in this background art section is only intended to enhance the overall understanding of the present invention and should not be regarded as an admission or any form of suggestion that this information constitutes prior art already known to those of ordinary skill in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a device for filling and decomposing an aqueous urea solution for vehicles to solve the deposition problem near the nozzle in the traditional solution and improve the conversion efficiency of the aqueous urea solution for vehicles and the uniformity of ammonia gas distribution.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: A device for filling and decomposing an aqueous urea solution for vehicles, comprising: A mixer, which is internally provided with an aqueous urea solution flow pipeline and is evenly distributed with capillary structures communicated with the flow pipeline; A urea pump, which is connected to the flow pipeline inside the mixer through a pipeline.

[0007] Preferably, the flow pipeline includes a two-way pipeline and a diffusion pipeline, and the two-way pipeline and the diffusion pipeline are evenly distributed in the mixer; the two-way pipeline is reserved with an inlet for the aqueous urea solution and is connected to the outlet of the urea pump.

[0008] Preferably, the aperture of the two-way pipeline is larger than that of the diffusion pipeline.

[0009] Preferably, the mixer is installed in the exhaust pipeline, and an SCR catalytic converter is installed at the rear thereof.

[0010] Compared with the prior art, the present invention has the following beneficial effects: (1) For the device for filling and decomposing the aqueous urea solution of the present invention, the filling of the aqueous urea solution is realized through the capillary structure, the traditional nozzle structure is cancelled, and the high-pressure injection device is not required. This not only simplifies the structure but also helps to reduce the high-risk deposition areas.

[0011] (2) For the device for filling and decomposing the aqueous urea solution of the present invention, the uniform distribution of ammonia is realized through the arrangement of the capillary structure and the flow field, which helps to eliminate the limitation problems of the atomization quality of the traditional nozzle on the ammonia distribution and urea decomposition.

[0012] (3) For the device for filling and decomposing the aqueous urea solution of the present invention, the filled aqueous urea solution is in full contact with the tail gas, which increases the contact area between the solution and the gas flow, accelerates the evaporation and decomposition of the aqueous urea solution, helps the intermediate products to diffuse into the gas flow in a gaseous state, inhibits the generation of urea decomposition by-products, promotes the decomposition of the intermediate gas products, helps to improve the selectivity of ammonia in the urea decomposition process, and further improves the conversion efficiency of the SCR system. Description of the Drawings

[0013] Figure 1 is a schematic diagram of the device of the present invention; Figure 2 is a schematic diagram of the mixer and the A-A cross-section of the present invention; Figure 3 is a schematic diagram of the mixer and the B-B cross-section of the present invention; Figure 4 is a schematic diagram of the flow pipeline and the capillary structure of the present invention; Figure 5 is a cross-sectional view of the exhaust pipeline; Main reference numeral description: 1. Mixer; 2. Urea pump; 3. Exhaust pipeline; 4. SCR catalytic converter; 11. Flow pipeline; 12. Capillary structure; 13. Inlet for aqueous urea solution; 111. Two-way pipeline; 112. Diffusion pipeline. Detailed Embodiments

[0014] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those skilled in the art based on the embodiments in the present invention without creative efforts belong to the scope of protection of the present invention.

[0015] In the description of the present invention, it should be noted that terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the invention.

[0016] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, terms such as "installation", "connection", "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the connection inside two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0017] Referring to the attached Figures 1-5 , the present invention provides a device for filling and decomposing aqueous urea solution for vehicles, which improves the filling and decomposition processes of aqueous urea solution in the engine exhaust after-treatment system. It mainly consists of a mixer 1, a urea pump 2, a flow pipeline 3, and a capillary structure 12.

[0018] The mixer 1 has a capillary structure 12, and a double-pass pipeline 111 and a diffusion pipeline 112 are arranged inside the mixer. The aperture of the double-pass pipeline 111 is larger than that of the diffusion pipeline 112. The mixer 1 does not rotate. In the double-pass pipeline 111, the fluid mainly flows driven by pressure, and in the diffusion pipeline 112, both pressure driving and capillary action act together; a urea aqueous solution inlet 13 is reserved in the double-pass pipeline 111 and is connected to the outlet of the urea pump 2.

[0019] When the SCR system operates, the urea pump 2 injects the urea aqueous solution into the double-pass pipeline 111. Under the driving of pressure, the urea aqueous solution fills the double-pass pipeline 111 and flows into the diffusion pipeline 112 under the dual action of pressure and capillary action, and penetrates to the surface of the mixer 1 through the capillary structure 12 of the mixer 1, and contacts with the high-temperature exhaust gas to undergo evaporation and decomposition.

[0020] Due to the sufficiently large interfacial contact area, the intermediate product isocyanic acid generated from the decomposition of urea can be promptly diffused into the gas stream, further undergoing a hydrolysis reaction to form ammonia gas, inhibiting the occurrence of side reactions and being conducive to improving the production rate of ammonia gas.

[0021] In this embodiment, the structure of the mixer 1 and the pipelines and capillary structures 12 inside it are evenly distributed, which can improve the uniformity of the distribution of the ammonia gas generated by the reaction and is conducive to eliminating the limitations of the atomization quality of traditional nozzles on the ammonia gas distribution and urea decomposition.

[0022] The vehicle urea aqueous solution filling and decomposition device of the present invention is installed in the exhaust pipeline 3, and an SCR catalytic converter 4 is installed at the rear. The filled urea aqueous solution is in full contact with the tail gas, increasing the contact area between the solution and the gas stream, accelerating the evaporation and decomposition of the urea aqueous solution, facilitating the diffusion of intermediate products into the gas stream in a gaseous state, inhibiting the formation of urea decomposition by-products, promoting the decomposition of intermediate gas products, improving the selectivity of ammonia gas during the urea decomposition process, and further enhancing the conversion efficiency of the SCR system.

[0023] When the SCR system stops operating, the urea pump 2 performs reverse suction, which can extract the residual urea aqueous solution in the internal pipelines of the mixer 1, avoiding the accumulation of urea aqueous solution in the pipelines during shutdown. The accumulated urea aqueous solution will precipitate solid urea, posing a deposition risk. The reverse suction function of the urea pump 2 can effectively avoid the deposition problem.

[0024] The vehicle urea aqueous solution filling and decomposition device of the present invention realizes the filling of urea aqueous solution through the capillary structure 12, eliminates the traditional nozzle structure, simplifies the structure, and does not require a high-pressure injection device. It can not only improve the selectivity and distribution uniformity of ammonia gas but also solve the deposition problem near the nozzle in the traditional solution. It is very practical and has good market application prospects.

[0025] The foregoing description of specific exemplary embodiments of the present invention is for purposes of illustration and exemplification. These descriptions are not intended to limit the present invention to the precise forms disclosed, and obviously, many changes and variations are possible in light of the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical applications, enabling those skilled in the art to implement and utilize various different exemplary embodiments of the present invention, as well as various different selections and changes. The scope of the present invention is intended to be defined by the claims and their equivalents.

Claims

1. A device for filling and decomposing aqueous urea solution for vehicles, characterized in that, Comprising: A mixer, inside which there is a urea aqueous solution flow pipeline, and capillary structures uniformly distributed and communicating with the flow pipeline; A urea pump, connected to the flow pipeline inside the mixer through a pipeline.

2. The urea aqueous solution filling and decomposition device for vehicles according to claim 1, characterized in that, The flow pipeline includes a double-pass pipeline and a diffusion pipeline, and the double-pass pipeline and the diffusion pipeline are uniformly distributed in the mixer; the double-pass pipeline has a reserved inlet for urea aqueous solution and is connected to the outlet of the urea pump.

3. The urea aqueous solution filling and decomposition device for vehicles according to claim 2, wherein The aperture of the double-pass pipeline is larger than the aperture of the diffusion pipeline.

4. The urea aqueous solution filling and decomposition device for vehicles according to claim 1, wherein, The mixer is installed in the exhaust pipeline, and an SCR catalytic converter is installed at its rear.

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