Selective catalytic reduction (SCR) reaction system

Abstract

The utility model provides a selective catalytic reduction (SCR) reaction system which comprises an outer shell, the two sides of the outer shell are connected with a gas inlet end and a gas outlet end respectively, the SCR reaction system further comprises an SCR mixing part, the SCR mixing part comprises an inner shell, an outer shell and a gas inlet pipe, the inner shell is arranged on the inner side of the outer shell, and the side, away from the gas inlet end, of the inner shell is connected with the outer shell through a first partition plate; a first spiral plate is connected to the outer surface of the inner shell, and a plurality of air inlets are formed in the portion, between the first spiral plate and the first partition plate, of the inner shell. The inner barrel is arranged in the inner shell, openings are formed in the two sides of the inner barrel, the inner barrel is fixedly connected with the first partition plate, a second spiral plate is fixed to the outer surface of the inner barrel, and a spiral air inlet pipe is connected into the inner barrel. In the whole process, the flowing paths of the urea solution and the tail gas flow are increased in the limited mixer space, the mixing degree of the tail gas and the urea solution is improved, meanwhile, the turbulent flow of the mixed gas can be further enhanced through the rotationally flowing urea solution and the tail gas flow, and the mixing degree of the tail gas and the urea solution is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of denitration, in particular to a selective catalytic reduction (SCR) reaction system. Background Art

[0002] The Selective Catalytic Reduction (SCR) system is one of the most effective measures to reduce NOx emissions from diesel engine exhaust. SCR technology reduces NOx in exhaust gas into nitrogen (N2) and water under the action of a reducing agent. Existing SCR technologies mostly use ammonia (NH3) produced by the decomposition of urea as a reducing agent.

[0003] The SCR system includes a mixer and a reactor. The mixer is connected to the exhaust pipe of the diesel engine and the reactor respectively, and a urea nozzle is arranged in the mixer. The urea sprayed from the nozzle undergoes a certain hydrolysis and pyrolysis reaction in the mixer to generate ammonia, and at the same time, after mixing with the exhaust gas containing NOx in the mixer, it flows into the reactor for reduction reaction.

[0004] For example, patent No. CN201810829182.1 discloses a vehicle system and its exhaust gas insulation mixing device, including a urea injection device, an SCR catalyst and an exhaust gas insulation mixing device, the exhaust gas insulation mixing device includes an outer cylinder and an inner cylinder, the front end of the outer cylinder is used to connect with the vehicle exhaust pipe, the rear end of the outer cylinder is used to connect with the front end of the SCR catalyst, the inner cylinder is made of heat-conducting material, the inner cavity of the inner cylinder forms a mixing channel for the circulation of a mixed gas formed by a mixture of exhaust gas and an injected urea aqueous solution, the annulus between the inner cylinder and the outer cylinder forms an insulation channel for the circulation of the insulation exhaust gas, and the outlet end of the inner cylinder is provided with a Venturi mixing section for fully mixing the mixed gas and the insulation exhaust gas.

[0005] However, due to the size limitations of the Venturi mixing section, tubular mixer and hemispherical mixer, the flow paths of urea and exhaust gas are relatively short, resulting in a shorter mixing time of urea and exhaust gas, which affects the degree of mixing of urea and exhaust gas to a certain extent. Utility Model Content

[0006] In view of the above problems, the utility model provides a selective catalytic reduction (SCR) reaction system.

[0007] A selective catalytic reduction (SCR) reaction system comprises an outer shell, the two sides of which are respectively connected to an air inlet end and an air outlet end. The selective catalytic reduction (SCR) reaction system also comprises an SCR mixing section, which comprises: an inner shell, which is arranged inside the outer shell, connected to the outer shell through a first partition on a side away from the air inlet end, and a first spiral plate is connected to the outer surface of the inner shell, and a plurality of air inlets are provided on the inner shell between the first spiral plate and the first partition; an inner cylinder, which is arranged inside the inner shell, has openings on both sides, is fixedly connected to the first partition, a second spiral plate is fixed to the outer surface of the inner cylinder, and a spiral air inlet pipe is connected inside the inner cylinder.

[0008] In a preferred embodiment, the selective catalytic reduction SCR reaction system further includes: a plurality of venturi tubes evenly arranged between the air intake end and the inner shell, and both sides of the plurality of venturi tubes are fixedly connected to the outer shell through a second partition.

[0009] In a preferred embodiment, the SCR mixing unit further comprises: a steel mesh layer, which is arranged on the inner side of the inner shell and on one side of the inner cylinder, and is arranged perpendicular to the inner cylinder.

[0010] In a preferred embodiment, the outer shell, the inner shell and the inner cylinder are coaxially arranged.

[0011] In a preferred embodiment, the selective catalytic reduction SCR reaction system further includes an SCR catalyst part, which includes a catalyst plate arranged inside the outer shell and between the gas outlet end and the inner cylinder.

[0012] In a preferred embodiment, the SCR catalyst part includes: a dividing plate, which is arranged inside the outer shell and between the catalyst plate and the inner cylinder.

[0013] In a preferred embodiment, the selective catalytic reduction SCR reaction system further includes: a urea pump installed on the air intake end.

[0014] 1. In the SCR reaction system of the present application, the mixed gas of exhaust gas and urea solution enters the outer shell from the air inlet end, and then enters the inner shell. Under the action of the first spiral plate, the mixed gas performs a rotational motion, and then enters the inner cylinder through the air inlet port, and is acted upon by the second spiral plate to perform a second rotational motion. Finally, it performs a third rotational motion through the spiral air inlet pipe and is then discharged from the air outlet end. The whole process increases the flow path of the urea solution and the exhaust gas flow within the limited mixer space, thereby improving the mixing degree of the exhaust gas and the urea solution. At the same time, the rotating urea solution and the exhaust gas flow can further enhance the turbulence of the mixed gas and improve the mixing degree of the exhaust gas and the urea solution.

[0015] 2. The SCR reaction system of the present application is provided with multiple Venturi tubes, so that multiple Venturi channels are formed at the front end of the inner shell, thereby accelerating the drainage and turbulence of the urea solution and the exhaust gas flow, enhancing the uniformity of the mixing of the urea solution and the exhaust gas flow, ensuring that the urea solution and the exhaust gas flow are fully mixed, and improving the denitrification efficiency for the subsequent catalytic action of the catalyst plate 6. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Other characteristics, features and advantages of the present invention will become clear by reading the following description of the exemplary embodiments with reference to the accompanying drawings. The accompanying drawings, which are incorporated into the specification and constitute a part of the specification, illustrate embodiments of the present invention and are used together with the description to explain the principles of the present invention. In these drawings, similar reference numerals are used to represent similar elements. The drawings described below are some embodiments of the present invention, not all embodiments. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A three-dimensional diagram of the SCR reaction system of the utility model;

[0018] Figure 2 The front view of the SCR reaction system of the utility model;

[0019] Figure 3 Internal structure diagram of the SCR reaction system of the utility model;

[0020] Figure 4 A cross-sectional view of the SCR reaction system of the utility model;

[0021] Figure 5 Sectional view of the SCR reaction system of the utility model at position AA;

[0022] Figure 6 Structural diagram of the SCR mixing unit of the utility model;

[0023] In the figure: 10, outer shell; 11, air inlet end; 12, air outlet end; 20, SCR mixing section; 30, inner shell; 31, first partition plate; 32, first spiral plate; 33, air inlet; 40, inner cylinder; 41, second spiral plate; 42, spiral air inlet pipe; 50, venturi tube; 51, second partition plate; 34, wire mesh layer; 21, SCR catalytic section; 60, catalyst plate; 61, equalizing plate; 13, urea pump. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the embodiment of the utility model clearer, the technical scheme in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model. It should be noted that the embodiments in this application and the features in the embodiments can be combined with each other arbitrarily without conflict.

[0025] The selective catalytic reduction SCR reaction system is described in detail below in conjunction with the accompanying drawings and embodiments. Example

[0026] A selective catalytic reduction (SCR) reaction system includes an outer shell 10, and the two sides of the outer shell 10 are respectively connected to an air inlet end 11 and an air outlet end 12. The selective catalytic reduction (SCR) reaction system also includes an SCR mixing section 20. The SCR mixing section 20 includes: an inner shell 30, which is arranged on the inner side of the outer shell 10, and is connected to the outer shell 10 through a first partition 31 on a side away from the air inlet end, and a first spiral plate 32 is connected to the outer surface of the inner shell 30, and a plurality of air inlets 33 are provided on the inner shell 30 between the first spiral plate 32 and the first partition 31; an inner cylinder 40, which is arranged in the inner shell 30, has openings on both sides, and is fixedly connected to the first partition 31, a second spiral plate 41 is fixed to the outer surface of the inner cylinder 40, and a spiral air inlet pipe 42 is connected in the inner cylinder 40.

[0027] The selective catalytic reduction SCR reaction system further includes an SCR catalyst unit 21 . The SCR catalyst unit 21 includes a catalyst plate 60 . The catalyst plate 60 is disposed inside the outer shell 10 and between the gas outlet end 12 and the inner cylinder 40 .

[0028] The selective catalytic reduction SCR reaction system further includes a urea pump 13 , which is installed on the intake end 11 .

[0029] The outer shell 10, the inner shell 30 and the inner cylinder 40 are coaxially arranged.

[0030] During operation, the mixed gas of exhaust gas and urea solution enters the outer shell 10 from the air inlet end 11, and then enters the inner shell 30. Under the action of the first spiral plate 32, the mixed gas performs a rotational motion, and then enters the inner cylinder 40 through the air inlet 33, and is acted upon by the second spiral plate 41 to perform a second rotational motion. Finally, it performs a third rotational motion through the spiral air inlet pipe 42, and is then discharged from the air outlet end 12. The entire process increases the flow path of the urea solution and the exhaust gas flow within a limited mixer space, and improves the mixing degree of the exhaust gas and the urea solution. At the same time, the rotating urea solution and the exhaust gas flow can further enhance the turbulence of the mixed gas and improve the mixing degree of the exhaust gas and the urea solution. Example

[0031] Example 2 is an improvement on Example 1, and the improvement includes: the selective catalytic reduction SCR reaction system also includes: a plurality of venturi tubes 50, which are evenly arranged between the intake end 11 and the inner shell 30, and both sides of the plurality of venturi tubes 50 are fixedly connected to the outer shell 10 through a second partition 51.

[0032] Specifically, by providing a plurality of venturi tubes 50, a plurality of venturi channels are formed at the front end of the inner shell 30, thereby accelerating the flow of the urea solution and the exhaust gas flow and disturbing the flow, thereby enhancing the uniformity of the mixing of the urea solution and the exhaust gas flow, ensuring that the urea solution and the exhaust gas flow are fully mixed, and improving the denitrification efficiency for the catalytic action of the subsequent catalyst plate 60.

[0033] Meanwhile, the provision of multiple Venturi tubes 50 is equivalent to a single Venturi tube, and the drainage and turbulence effects are stronger, thereby enhancing the uniformity of mixing of the urea solution and the exhaust gas flow, and ensuring that the urea solution and the exhaust gas flow are fully mixed. Example

[0034] Embodiment 3 is an improvement on Embodiment 1, and the improvement includes: the SCR mixing unit 20 further includes: a steel mesh layer 34 disposed inside the inner shell 30 and on one side of the inner cylinder 40 , and disposed perpendicularly to the inner cylinder 40 .

[0035] The provision of the steel wire mesh layer 34 is beneficial to the breakage and decomposition of the urea aqueous solution droplets, which accelerates the mixing of urea and exhaust gas and avoids the generation of urea crystals. Example

[0036] Embodiment 4 is an improvement on Embodiment 1, and the improvement includes:

[0037] The SCR catalyst unit 21 further includes a dividing plate 61 disposed inside the outer shell 10 and between the catalyst plate 60 and the inner cylinder 40 .

[0038] By providing the equalizing plate 61 , the mixed gas of the urea solution and the tail gas in front of the catalyst plate 60 is made uniform, which facilitates the reaction with the catalyst plate 60 and improves the denitrification efficiency of the device.

[0039] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that an article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such article or device. In the absence of further restrictions, the elements defined by the sentence "includes..." do not exclude the existence of other identical elements in the article or device including the elements.

[0040] The above embodiments are only used to illustrate the technical solution of the utility model but not to limit it. The utility model is described in detail with reference to the preferred embodiments. It should be understood by those skilled in the art that the technical solution of the utility model can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the utility model, and all should be included in the scope of the claims of the utility model.

Claims

1. A selective catalytic reduction (SCR) reaction system, comprising an outer shell (10), wherein two sides of the outer shell (10) are respectively connected to an air inlet (11) and an air outlet (12), wherein: The selective catalytic reduction (SCR) reaction system further comprises an SCR mixing unit (20), wherein the SCR mixing unit (20) comprises: An inner shell (30) is arranged inside the outer shell (10), and is connected to the outer shell (10) via a first partition (31) on a side away from the air inlet end, and a first spiral plate (32) is connected to the outer surface of the inner shell (30), and a plurality of air inlets (33) are provided on the inner shell (30) between the first spiral plate (32) and the first partition (31); An inner cylinder (40) is arranged in the inner shell (30), has openings on both sides, and is fixedly connected to the first partition plate (31). A second spiral plate (41) is fixed to the outer surface of the inner cylinder (40), and a spiral air intake pipe (42) is connected inside the inner cylinder (40).

2. The selective catalytic reduction (SCR) reaction system according to claim 1, characterized in that: The selective catalytic reduction SCR reaction system also includes: A plurality of venturi tubes (50) are evenly arranged between the air inlet end (11) and the inner shell (30), and two sides of the plurality of venturi tubes (50) are fixedly connected to the outer shell (10) via a second partition plate (51).

3. The selective catalytic reduction (SCR) reaction system according to claim 1, characterized in that: The SCR mixing unit (20) further includes: The wire mesh layer (34) is arranged inside the inner shell (30) and on one side of the inner cylinder (40), and is arranged perpendicular to the inner cylinder (40).

4. The selective catalytic reduction (SCR) reaction system according to claim 1, characterized in that: The outer shell (10), the inner shell (30), and the inner cylinder (40) are coaxially arranged.

5. The selective catalytic reduction (SCR) reaction system according to claim 1, characterized in that: The selective catalytic reduction (SCR) reaction system further comprises an SCR catalyst unit (21), wherein the SCR catalyst unit (21) comprises: The catalyst plate (60) is arranged inside the outer shell (10) and between the gas outlet end (12) and the inner cylinder (40).

6. The selective catalytic reduction (SCR) reaction system according to claim 5, characterized in that: The SCR catalyst unit (21) comprises: The equalizing plate (61) is arranged inside the outer shell (10) and between the catalyst plate (60) and the inner cylinder (40).

7. The selective catalytic reduction (SCR) reaction system according to claim 1, characterized in that: The selective catalytic reduction SCR reaction system also includes: A urea pump (13) is mounted on the air intake end (11).

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