RU2831971C2 - Engine exhaust gas treatment mixer and u-shaped engine exhaust gas treatment system - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: group of inventions relates to treatment of engine exhaust gases. Engine exhaust gas treatment mixer comprises a bearing support, a vortex mixer mounted on the upper end of the bearing support, long-tube mixer, which is installed on the lower end of the bearing support and is in communication with the vortex mixer, and a perforated plate balancing flow rate, which is installed on the lower end of the bearing support and is located at the side of the long-tube mixer. Vortex mixer has a housing which has a vortex shape from the inside to the outside. Vortex channel for a fluid medium is formed in the housing. Fluid vortex channel is configured to conduct an exhaust gas flow for its supply along a spiral into the central area of urea mixing of the vortex channel for the fluid medium from outside. Sealing plate is provided at the lower end of the housing, which is equipped with an outlet for fluid medium, which is connected to the central area of urea admixture. Long-tube mixer comprises a tubular housing, wherein on the peripheral wall of the lower end of the tubular housing there are a plurality of exhaust holes. U-shaped engine exhaust gas treatment system comprises a diesel oxidation catalyst (DOC) unit, a diesel particulate filter (DPF) unit connected to the downstream end of the DOC unit, a selective catalytic reduction (SCR) unit and an engine exhaust gas treatment mixer. Fluid inlet is connected to the DPF unit and the fluid outlet is connected to the SCR unit; and the DOC unit, the DPF unit, the engine exhaust gas treatment mixer and the SCR unit are arranged in a U-shape.

EFFECT: increased homogeneity of mixing flow of exhaust gas and NH₃ and uniformity of flow rate of flow of exhaust gas, reduced amount of introduced urea, elimination of urea crystallisation effect.

9 cl, 7 dwg

Description

[0001] This application claims priority to Chinese Patent Application No. 202110677711.2, entitled "ENGINE AFTER-TREATMENT MIXER AND U-SHAPED ENGINE AFTER-TREATMENT SYSTEM", filed on June 18, 2021, in the National Intellectual Property Administration of China, which is incorporated herein by reference in its entirety.

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

[0002] The present application relates to the technical field of engine exhaust gas treatment and, in particular, to a mixer for aftertreatment and a U-shaped engine aftertreatment system.

LEVEL OF TECHNOLOGY

[0003] An after-treatment mixer (SCR mixer (Selective Catalytic Reduction Mixer)) is used to improve the mixing uniformity of urea and exhaust gas and improve the NOx conversion efficiency. The conventional mixer has the following disadvantages. Under the action of the exhaust gas flow, some of the urea droplets in the urea stream are difficult to atomize and decompose, resulting in non-uniform mixing of _NH3 separated from the liquid urea and the exhaust gas flow, and uniformity of the gas mixture flow velocity cannot be ensured. The deterioration of _NH3 uniformity and velocity uniformity makes it necessary to inject a larger amount of urea to completely convert NOx in the exhaust gas, and urea crystallization becomes more likely to occur at a low exhaust temperature and a low exhaust gas flow velocity.

ESSENCE OF THE INVENTION

[0004] In order to overcome the disadvantages of the above conventional technology, the object of the present application is to provide an after-treatment mixer and an after-treatment system for an engine that can improve the uniformity of mixing of an exhaust gas flow and _NH3 at the inlet of an SCR unit and the uniformity of the flow rate of the mixed gas, can reduce the amount of urea introduced, and can effectively avoid the phenomenon of urea crystallization that occurs at a low exhaust temperature and a low flow rate of the exhaust gas.

[0005] In order to solve the problems existing in the above-mentioned conventional technology, a mixer for additional processing according to one embodiment of the present application is provided. The mixer for additional processing includes a support support, a vortex mixer installed on an upper end of the support support, a long-tube mixer which is installed on a lower end of the support support and is in communication with the vortex mixer, and a flow rate equalizing perforated plate which is installed on the lower end of the support support and is located at the side of the long-tube mixer.

[0006] A vortex mixer includes a housing that has a vortex shape from the inside to the outside, where a vortex channel for a fluid medium is formed in the housing, and the vortex channel for a fluid medium is designed with the possibility of conducting a flow of exhaust gas for its entry in a spiral into a central region for mixing urea of the vortex channel for a fluid medium from the outside; and at the lower end of the housing a sealing plate is provided, where the sealing plate is provided with an outlet for a fluid medium that communicates with the central region for mixing urea.

[0007] The long-tube mixer includes a tubular body, and a plurality of exhaust holes are formed on a peripheral wall of a lower end of the tubular body.

[0008] In one embodiment, the support support includes a fixed plate on which a communication hole is provided through which the vortex mixer communicates with the long-tube mixer.

[0009] In one embodiment, a plurality of holes may be formed on the peripheral wall of the inner layer and/or the peripheral wall of the outer layer of the housing to reduce back pressure.

[0010] In one embodiment, a plurality of backpressure relief holes may be provided on a portion of the sealing plate around the fluid outlet.

[0011] In one embodiment, each of the exhaust openings is a circular opening. In an alternative embodiment, each of the exhaust openings is an elongated opening extending along the direction of the axis of the tubular body.

[0012] In one embodiment, a mixer for further processing includes a mixer housing having an opening on a side portion and an end cap located on the open end of the mixer housing. A support support, a vortex mixer, a long-tube mixer and a flow-equalizing perforated plate are each located in the mixer housing, and an inlet for a urea solution that communicates with a central urea mixing region is provided at a portion of the mixer housing, at the top of the vortex mixer.

[0013] The end cover is formed with an inlet for a fluid medium corresponding to the side portion of the vortex mixer, and with an outlet for a fluid medium corresponding to the flow rate equalizing perforated plate.

[0014] In one embodiment, a baffle plate is provided in a portion of the mixer housing below the tubular body.

[0015] In one embodiment, the baffle plate is provided with holes to reduce back pressure.

[0016] According to one embodiment of the present application, a U-shaped engine aftertreatment system is further provided. The U-shaped engine aftertreatment system includes a diesel oxidation catalyst (DOC) unit, a diesel particulate filter (DPF) unit connected to the downstream end of the DOC unit, and a selective catalytic reduction (SCR) unit. In addition, the U-shaped engine aftertreatment system includes a mixer for aftertreatment. The fluid inlet is connected to the DPF unit, and the fluid outlet is connected to the SCR unit.

[0017] The DOC unit, DPF unit, aftertreatment mixer and SCR unit are arranged in a U-shape.

[0018] By means of the above technical solutions, the useful results achieved by the present application are as follows.

[0019] The mixer for additional processing according to the present application includes a supporting support, a vortex mixer mounted on the upper end of the supporting support, a long-tube mixer which is mounted on the lower end of the supporting support and is in communication with the vortex mixer, and a flow rate equalizing perforated plate which is mounted on the lower end of the supporting support and is located at the side of the long-tube mixer. The vortex mixer includes a housing which has a vortex shape from the inside to the outside, where a vortex channel for a fluid is formed in the housing, and the vortex channel for a fluid is configured to conduct a flow of exhaust gas for its entry in a spiral into a central region for mixing urea of the vortex channel for a fluid from the outside; and a sealing plate is provided at the lower end of the housing, where the sealing plate is provided with an outlet for a fluid which communicates with the central region for mixing urea. The long-tube mixer includes a tubular body, and a plurality of exhaust holes are formed on the peripheral wall of the lower end of the tubular body. The U-shaped engine aftertreatment system includes the above-mentioned mixer for aftertreatment.

[0020] The vortex mixer at the upper end first directs the exhaust gas flow entering in a spiral into the central region of urea mixing in the vortex fluid channel from the outside, which prevents the exhaust gas flow from flowing directly to the lower part, prolongs the period of time during which the exhaust gas flow is in contact with the urea solution, and promotes rapid evaporation, atomization and decomposition of the urea solution. The intensive mixing caused by the spiral flow of the exhaust gas flow makes it possible to completely mix NH ₃ formed by atomization and decomposition of the urea solution with the exhaust gas flow, and promotes easier removal of the urea solution from the wall of the housing, preventing the occurrence of urea crystallization. The long-tube mixer at the lower end can further expand the mixing area, enhance the mixing of the exhaust gas flow, extend the mixing time of the exhaust gas flow and _NH3 , and further improve the uniformity of mixing of _NH3 and the exhaust gas flow at the inlet of the SCR unit. By means of the exhaust holes on the long-tube mixer and the flow rate equalizing perforated plate, the uniformity of the flow velocity of the exhaust gas flow at the inlet of the SCR unit can be improved.

[0021] In summary, by means of the present application, the uniformity of mixing of the exhaust gas flow and NH ₃ at the inlet of the SCR unit and the uniformity of the flow rate of the exhaust gas flow can be improved, the amount of urea introduced can be reduced, and the phenomenon of urea crystallization that occurs at a low exhaust temperature and a low flow rate of the exhaust gas can be effectively prevented.

BRIEF DESCRIPTION OF DRAWINGS

[0022] FIG. 1 is a schematic view of the structure of a further processing mixer according to one embodiment of the present application;

[0023] FIG. 2 is an exploded view of the post-processing mixer structure shown in FIG. 1;

[0024] FIG. 3 is a view of the structure of the support support, the vortex mixer, the long tube mixer, and the flow equalizing perforated plate in FIG. 2;

[0025] FIG. 4 is a schematic view of the structure of the vortex mixer of FIG. 3 in another perspective view;

[0026] FIG. 5 is a top view of the vortex mixer shown in FIG. 3;

[0027] FIG. 6 is a schematic view of the structure of an engine aftertreatment system according to one embodiment of the present application;

[0028] FIG. 7 is a cross-sectional view of the engine aftertreatment system of FIG. 6;

[0029] The reference positions in the drawings are listed as follows:

DETAILED DESCRIPTION OF IMPLEMENTATION OPTIONS

[0030] In order to more clearly illustrate the objectives, technical solutions and advantages of the present application, the present application will be further described in detail below in conjunction with the drawings and embodiments. It should be understood that the embodiments described herein are presented for explanation only, but not to limit the present application.

[0031] First embodiment

[0032] As shown in the figures from FIG. 1 to FIG. 5, a mixer "b" for additional processing according to the first embodiment is shown. The mixer "b" for additional processing specifically includes a supporting support 1, a vortex mixer 2 installed at the upper end of the supporting support 1, a long-tube mixer 3 which is located at the lower end of the supporting support 1 and is in communication with the vortex mixer 2, and a flow rate equalizing perforated plate 4 which is installed at the lower end of the supporting support 1 and is located at the side of the long-tube mixer 3. The vortex mixer 2 includes a housing 21 which has a shape in the form of a vortex from the inside to the outside, and is extended along the direction of the axis of the long-tube mixer 3. The housing 21 can be formed by bending and winding a single sheet, or by welding many sheets in sequence with the end of one of the sheets, being welded to the head of the next one of the sheets, following the vortex line. The vortex channel 22 of the fluid medium is intended to direct the flow of the exhaust gas in a spiral to enter the central region 23 of mixing the urea of the vortex channel 22 of the fluid medium from the outside. The sealing plate 24 is located at the lower end of the housing 21, where the sealing plate 24 is provided with an outlet 25 for the fluid medium, which communicates with the central region 23 of mixing the urea. The long-tube mixer 3 includes a tubular housing 31, and on the peripheral wall of the lower end of the tubular housing 31 a plurality of exhaust openings 32 are located.

[0033] The exhaust gas flow enters the vortex mixer 2 from the side portion and enters the central urea mixing region 23, being guided by the vortex fluid channel 22 so as to be completely mixed with the urea solution.

[0034] The exhaust gas flow exiting through the exhaust openings 32 enters the SCR unit after passing through the flow equalizing perforated plate 4.

[0035] In this embodiment, each of the exhaust openings 32 is a circular opening, and in some embodiments, each of the exhaust openings 32 is an elongated opening extending along the direction of the axis of the tubular body 31.

[0036] In this embodiment, the supporting support 1 includes a fixed plate 11 on which a communication hole 12 is placed, through which the vortex mixer 2 communicates with the long-tube mixer 3.

[0037] In order to reduce the back pressure and ensure the uniformity of the flow of the exhaust gas, in this embodiment, a plurality of back pressure reducing holes "a" may be optionally provided on the peripheral wall of the inner layer and/or the peripheral wall of the outer layer of the body 21. Alternatively, a plurality of back pressure reducing holes "a" may be optionally provided on a part of the sealing plate 24, around the fluid outlet 25. Each of the back pressure reducing holes "a" is not unique in shape, and may be a circular hole, a hole with a tapering shape, or an elongated hole. The position and number of the back pressure reducing holes "a" are not limited as long as the back pressure can be reduced and a uniform flow of the exhaust gas can be ensured.

[0038] The flow equalizing perforated plate 4 is not unique in shape, and may be round, semicircular, or square. The through holes in the flow equalizing perforated plate 4 are not unique in shape, and may be round holes, holes with a tapering shape, or elongated holes.

[0039] The mixer "b" for further processing in this embodiment further includes a mixer housing 5 having an opening at the side portion, and an end cover 6 disposed at the open end of the mixer housing 5. The supporting support 1, the vortex mixer 2, the long-tube mixer 3 and the flow rate equalizing perforated plate 4 are each disposed in the mixer housing 5, and an inlet 51 for the urea solution that communicates with the central urea mixing region 23a is provided at the top of the mixer housing 5 (that is, at the part of the mixer housing 5, at the top of the vortex mixer 2). The end cover 6 is formed with an inlet 61 for the fluid corresponding to the side portion of the vortex mixer 2, and with an outlet 62 for the fluid corresponding to the flow rate equalizing perforated plate 4.

[0040] In order to further improve the uniformity of mixing of NH ₃ and the exhaust gas flow, in this embodiment, a baffle corrugated plate 52 is provided at a portion of the mixer housing 5, below the tubular body 31, to buffer and direct the exhaust gas flow flowing through the lower port of the tubular body 31. The baffle corrugated plate 52 is provided with holes "a" for reducing back pressure to ensure a uniform flow of the exhaust gas.

[0041] Based on the description of the above structure, the operating principle of this embodiment will be described below.

[0042] The vortex channel for the fluid 22 in the vortex mixer 2 at the upper end directs the flow of the exhaust gas entering in a spiral into the central region 23 for mixing the urea from the outside, which prevents the flow of the exhaust gas from flowing directly to the lower part, prolongs the period of time during which the flow of the exhaust gas contacts the urea solution (which vertically enters the central region 23 for mixing the urea through the inlet 51 for the urea solution), and promotes rapid evaporation, atomization and decomposition of the urea solution. The intensive mixing caused by the spiral flow of the exhaust gas stream makes it possible to completely mix NH ₃ formed by atomization and decomposition of the urea solution with the flow of the exhaust gas, and promotes easier removal of the urea solution from the peripheral wall of the housing 21, preventing the occurrence of crystallization of urea. In addition, the long-pipe mixer 3 at the lower end can further expand the mixing area, enhance the mixing of the exhaust gas flow, extend the mixing time of the exhaust gas flow and NH ₃ , and further improve the uniformity of mixing of NH ₃ and the exhaust gas flow at the inlet of the SCR unit. By means of the exhaust holes 32 on the long-pipe mixer 3 and the flow rate equalizing perforated plate 4, the uniformity of the flow velocity of the exhaust gas flow at the inlet of the SCR unit can be improved.

[0043] Second Embodiment

[0044] As shown in FIG. 6 and FIG. 7, a U-shaped engine after-treatment system according to a second embodiment is shown. The U-shaped engine after-treatment system includes a DOC unit 7, a DPF unit 8 connected to a downstream end of the DOC unit 7, and an SCR unit 9. In addition, the U-shaped engine after-treatment system includes a mixer "b" for after-treatment according to the first embodiment. A fluid inlet 61 is connected to the DPF unit 8, and a fluid outlet 62 is connected to an upstream end (inlet) of the SCR unit. The DOC unit 7, the DPF unit 8, the mixer "b" for after-treatment, and the SCR unit 9 are arranged in a U-shape.

[0045] The specific principles are described in the first embodiment and will not be repeated here.

[0046] Throughout this description, reference may be made to these embodiments with respect to the same or similar parts.

[0047] In summary, by means of the present application, the uniformity of mixing of the exhaust gas flow and _NH3 at the inlet of the SCR unit and the uniformity of the flow rate of the exhaust gas flow can be improved, the amount of urea introduced can be reduced, and the phenomenon of urea crystallization that occurs at a low exhaust temperature and a low flow rate of the exhaust gas can be effectively prevented.

[0048] The foregoing represents only preferred embodiments of the present application and is not intended to be limiting of the present application. Any modifications, equivalent replacements and improvements made within the meaning and principles of the present application shall be included within the scope of the legal protection of the present application.

Claims (17)

1. A mixer for treating engine exhaust gases, comprising: a supporting support, a vortex mixer mounted on the upper end of the supporting support; a long-tube mixer which is mounted on the lower end of the support support and is in communication with the vortex mixer; and a flow equalizing perforated plate which is mounted on the lower end of the support support and located at the side of the long-tube mixer; and a vortex mixer comprises a housing which has a vortex shape from the inside out, wherein a vortex channel for a fluid medium is formed in the housing, and the vortex channel for a fluid medium is designed with the possibility of conducting a flow of exhaust gas for its entry in a spiral into a central region for mixing urea of the vortex channel for a fluid medium from the outside; and at the lower end of the housing a sealing plate is provided, wherein the sealing plate is provided with an outlet for a fluid medium which communicates with the central region for mixing urea; and The long-tube mixer comprises a tubular body, and a plurality of exhaust holes are formed on a peripheral wall of the lower end of the tubular body. 2. A mixer for processing engine exhaust gases according to claim 1, in which the supporting support comprises a fixed plate on which a communication opening is provided, through which the vortex mixer communicates with the long-tube mixer. 3. A mixer for treating engine exhaust gases according to claim 1, in which a plurality of holes are made on the peripheral wall of the inner layer and/or the peripheral wall of the outer layer of the housing to reduce back pressure. 4. A mixer for treating engine exhaust gases according to claim 1, wherein a plurality of holes are formed on a portion of the sealing plate around the outlet for the fluid medium to reduce back pressure. 5. A mixer for treating engine exhaust gases according to claim 1, wherein each of the exhaust openings is a circular opening or each of the exhaust openings is an elongated opening extended along the axial direction of the tubular body. 6. A mixer for treating engine exhaust gases according to claim 1, wherein the mixer for treating engine exhaust gases comprises a mixer housing having an opening on a side portion and an end cap located on the open end of the mixer housing; wherein the supporting support, the vortex mixer, the long-tube mixer and the flow-equalizing perforated plate are in each case located in the mixer housing; wherein at a part of the mixer housing, at the top of the vortex mixer, an inlet is provided for a urea solution, which communicates with the central region of urea mixing; wherein the end cap is provided with an inlet for a fluid corresponding to the side portion of the vortex mixer and an outlet for a fluid corresponding to the flow-equalizing perforated plate. 7. A mixer for treating engine exhaust gases according to item 6, in which a corrugated baffle plate is provided in the part of the mixer casing below the tubular body. 8. A mixer for treating engine exhaust gases according to claim 7, in which the baffle corrugated plate is provided with an opening for reducing back pressure. 9. A U-shaped engine exhaust gas treatment system comprising: a diesel oxidation catalyst (DOC) unit, a diesel particulate filter (DPF) unit connected to the downstream end of the DOC unit, and a selective catalytic reduction (SCR) unit, wherein The U-shaped engine exhaust gas treatment system further comprises a mixer for treating engine exhaust gases according to any one of claims 6-8, wherein the fluid inlet is connected to the DPF unit, and the fluid outlet is connected to the SCR unit; and The DOC unit, DPF unit, mixer for treating engine exhaust gases and SCR unit are arranged in a U-shape.