A high-voltage SCR evaporation mixing device and its usage method

Abstract

The present invention discloses a high-pressure SCR evaporation mixing device and a using method thereof, which relates to the technical field of diesel engine exhaust gas purification. It solves the problems of large volume and inconvenient maintenance of the existing high-pressure SCR evaporation mixing structure, and facilitates use and maintenance. The specific solution is as follows: It includes a mixing pipe, a first heat-insulating layer arranged on the outer wall of the mixing pipe, a spray gun, and a static mixer detachably installed in the mixing pipe. The static mixer is close to the air inlet end of the mixing pipe. The static mixer contains a porous cover, and a plurality of guide vanes are fixedly arranged at intervals along the circumferential direction on the outer edge of the porous cover for blocking the flue gas to reduce its speed and generate vortices and rotations. The spray gun is detachably installed on the mixing pipe, and the nozzle of the spray gun is located inside the mixing pipe and sprays in a direction away from the static mixer. High-temperature infrared band high-emissivity coatings are provided on the inner wall of the mixing pipe and the surface of the static mixer.

Description

Technical Field

[0001] The present invention relates to the technical field of diesel engine exhaust gas purification, and particularly to a high-pressure SCR evaporation mixing device and a usage method thereof. Background Art

[0002] A high-pressure SCR system needs to be provided with a mixing and evaporation structure. An aqueous urea solution is atomized and sprayed into high-temperature exhaust gas in the evaporation mixing structure. After the water in the droplets evaporates, ammonia gas required for the SCR reaction is produced through the pyrolysis of urea and the hydrolysis of isocyanic acid. Inside the mixing and evaporation structure, the aqueous urea solution needs to be atomized into relatively uniform tiny droplets in the exhaust gas, and then the droplets are quickly and fully evaporated into a gaseous state, mixed with the exhaust gas sufficiently, and urea and isocyanic acid are converted into a sufficient amount of ammonia gas through physical and chemical processes such as pyrolysis and hydrolysis in the mixing pipeline and the subsequent short connecting pipeline; meanwhile, it is necessary to prevent the atomized droplets from directly touching the internal components of the mixing pipeline and ensure that the pressure drop is within a reasonable range.

[0003] The inventor found that the existing marine high-pressure SCR evaporation mixing structures are generally long, which brings certain difficulties to the shipyard in arranging the SCR connecting pipelines. It is necessary for SCR suppliers and shipbuilders to continuously coordinate, and even change the design of the originally finalized SCR mixing and evaporation structure, reducing the universality and adaptability of the product. The main reason is that the urea solution cannot be quickly and fully converted into a gaseous state within a limited pipeline length, and it is necessary to arrange pipelines with larger sizes to ensure a larger evaporation and mixing space; at the same time, the SCR mixing and evaporation structure also has problems such as inconvenient maintenance and repair, and it is unable to effectively avoid and handle crystallization. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a high-pressure SCR evaporation mixing device and a usage method thereof. A static mixer for blocking the flue gas to slow it down and generate vortices and rotations is provided at the air inlet end of the mixing pipe, which can extend the mixing path and reduce the volume of the device. The porous cover and the guide vane cooperate with each other, so that the flue gas can form a low-pressure and low-speed recirculation disturbance area near the urea solution injection point. The urea solution droplets can quickly evaporate and undergo gas-phase reactions in the recirculation disturbance area, avoiding the formation of obvious crystalline substances on the surface of the static mixer and the inner wall of the mixing pipe, reducing the maintenance frequency, and solving the problems of large volume and inconvenient maintenance and repair of the existing high-pressure SCR evaporation mixing structure.

[0005] In order to achieve the above purpose, the present invention is realized through the following technical solutions:

[0006] In a first aspect, the present invention provides a high-pressure SCR evaporation mixing device, which includes a mixing pipe, a first heat-insulating layer provided on the outer wall of the mixing pipe, a spray gun, and a static mixer detachably installed in the mixing pipe. The static mixer is close to the air inlet end of the mixing pipe. The static mixer includes a porous cover, and a plurality of guide vanes are fixedly arranged at intervals along the circumferential direction on the outer edge of the porous cover for blocking the flue gas to reduce its speed and generate vortices and rotations. The spray gun is detachably installed on the mixing pipe, and the nozzle of the spray gun is located inside the mixing pipe and sprays in a direction away from the static mixer. High-temperature infrared band high-emissivity coatings are provided on the inner wall of the mixing pipe and the surface of the static mixer.

[0007] As a further implementation manner, the mixing pipe is composed of a pipe body, first flanges fixedly installed at both ends of the pipe body, a maintenance hole opened on the pipe body, and a spray gun installation hole. A second flange is fixedly installed on the maintenance hole, a third flange is installed on the spray gun installation hole, an upper fixing seat and an inner cover plate are fixedly installed in the maintenance hole, and the inner cover plate is located above the upper fixing seat.

[0008] As a further implementation manner, the upper fixing seat is close to the inner wall of the pipe body, and a plurality of stud bolts connected to the inner cover plate are fixedly provided on the upper surface of the upper fixing seat. The second flange is connected to the maintenance hole flange cover, and a second heat-insulating layer is installed between the maintenance hole flange cover and the inner cover plate.

[0009] As a further implementation manner, a lower fixing seat is fixedly provided in the pipe body, and the upper fixing seat is located directly above the lower fixing seat for the disassembly and installation of the static mixer.

[0010] As a further implementation manner, a plurality of relatively arranged fixing grooves are provided on the upper surface of the upper fixing seat, and the fixing grooves are uniformly arranged along the axial direction of the upper fixing seat. The axial direction of the lower fixing seat is the same as that of the upper fixing seat, and a plurality of positioning holes are uniformly arranged at intervals along the axial direction of the lower fixing seat to cooperate with the fixing grooves to fix and adjust the position of the static mixing.

[0011] As a further implementation manner, an upper connecting rod is fixedly provided at the top of the porous cover, a fixing rod for connecting with the upper fixing seat is fixedly provided on the upper connecting rod, and a lower connecting rod connected to the lower fixing seat is fixedly provided at the bottom of the porous cover.

[0012] As a further implementation manner, the diameter of the porous cover is smaller than the inner diameter of the mixing pipe, a plurality of ventilation holes allowing the flue gas to pass through are opened on the porous cover, and the porous cover protrudes toward the air inlet end of the mixing pipe.

[0013] As a further implementation manner, a shallow groove for installing a spring washer is provided on the upper plane at the end of the fixing rod.

[0014] Second aspect, the present invention provides a method for using a high-pressure SCR evaporation mixing device, which is as follows:

[0015] Insert the static mixer into the pipeline main body through the inspection hole, and insert the lower connecting rod into the positioning hole;

[0016] Install the upper fixing rod in the fixing groove, install the spring washer in the shallow groove of the fixing rod, install the inner cover plate on the stud of the upper fixing seat and tighten the bolt. Finally, install the second heat insulation layer and the inspection hole flange cover;

[0017] When it is necessary to disassemble the static mixer, remove the inspection hole flange cover, the second heat insulation layer, the inner cover plate and the spring washer in sequence, pull up and adjust the angle of the static mixer, and pull out the static mixer as a whole from the mixing pipe.

[0018] As a further implementation method, when it is necessary to adjust the position of the static mixer in the evaporation mixing pipeline, remove the inspection hole flange cover, the second heat insulation layer, the inner cover plate and the spring washer in sequence;

[0019] Pull up the fixing rod to separate the static mixer from the upper fixing seat and the lower fixing seat, and reinstall the fixing rod and the lower connecting rod of the static mixer into the specified fixing groove and positioning hole;

[0020] Reset the spring washer, the inner cover plate, the second heat insulation layer and the inspection hole flange cover in sequence and tighten the bolt.

[0021] The beneficial effects of the above-mentioned present invention are as follows:

[0022] (1) The present invention provides a static mixer at the air inlet end of the mixing pipe to block the flue gas to reduce its speed and generate eddy currents and rotations, which can extend the mixing path, reduce the volume of the device, and facilitate maintenance; the porous cover and the guide vane cooperate with each other to form a low-pressure and low-speed reflux disturbance area near the urea solution injection point. The urea solution droplets can quickly evaporate and undergo gas-phase reactions in the reflux disturbance area, avoiding obvious crystallization on the surface of the static mixer and the inner wall of the mixing pipe, and reducing the maintenance frequency.

[0023] (2) The inner wall of the mixing pipe and the surface of the static mixer of the present invention are both provided with high-temperature infrared band high-emissivity coatings, which increase the radiant heat exchange amount between the surface of the static mixer and the inner wall of the mixing pipe and the urea solution evaporation area, increase the temperature of the low-temperature exhaust gas area, can accelerate the evaporation of the urea solution droplets and enhance the gas-phase reaction, and do not require an overly long pipeline path, further reducing the overall size of the device.

[0024] (3) The setting of the inspection hole of the present invention facilitates the disassembly and assembly of the static mixer and the maintenance. The settings of the first thermal insulation layer and the second thermal insulation layer make the temperatures of the surface of the static mixer and the inner wall of the pipeline main body the same as the temperature of the waste gas, effectively ensuring that the high-temperature waste gas, the surface of the static mixer, and the inner wall of the pipeline main body will conduct radiative heat exchange with the low-temperature waste gas area. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings forming a part of this specification are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0026] Figure 1 is a schematic diagram of the overall structure of a high-pressure SCR evaporation mixing device according to one or more embodiments of the present invention;

[0027] Figure 2 is an exploded structure diagram of a high-pressure SCR evaporation mixing device according to one or more embodiments of the present invention;

[0028] Figure 3 is Figure 2 a partial enlarged structure diagram of the structure at B shown;

[0029] Figure 4 is Figure 2 a partial enlarged structure diagram of the structure at C shown;

[0030] Figure 5 is a side view structure diagram of a high-pressure SCR evaporation mixing device according to one or more embodiments of the present invention;

[0031] Figure 6 is Figure 5 an A-A sectional structure diagram of the structure shown;

[0032] Figure 7 is a disassembly and assembly diagram of a static mixer and a spray gun according to one or more embodiments of the present invention;

[0033] Figure 8 is a structure diagram of a static mixer according to one or more embodiments of the present invention;

[0034] In the figure: The distances or sizes between each part are exaggerated for showing the positions of each part, and the schematic diagram is only for illustration;

[0035] Among them, 1. mixing pipe; 1_1 pipeline main body; 1_2, first flange; 1_3, inspection hole flange cover; 1_4, second thermal insulation layer; 1_5, inner cover plate; 1_6, second flange; 1_7, upper fixing seat; 1_7_1, fixing groove; 1_7_2, stud; 1_8, lower fixing seat; 1_8_1, positioning hole; 1_9, third flange;

[0036] 2. The first thermal insulation layer;

[0037] 3. Spray gun; 3_1. Flange; 3_2. Spray gun body; 3_3. Nozzle;

[0038] 4. Static mixer; 4_1. Fixed rod; 4_1_1. Spring washer; 4_2. Upper connecting rod; 4_3. Porous cover; 4_4. Deflector; 4_5. Lower connecting rod. Detailed implementation mode

[0039] It should be noted that the following detailed description is illustrative and aims to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0040] As introduced in the background art, the urea solution cannot be quickly and fully converted into gas within a limited pipeline length, and larger-sized pipelines need to be arranged to ensure a larger evaporation and mixing space, resulting in the generally long existing marine high-pressure SCR evaporation and mixing structures, causing difficulties in arranging SCR connection pipelines and maintenance and repair in shipyards. To solve the above technical problems, the present invention proposes a high-pressure SCR evaporation and mixing device and its usage method.

[0041] Embodiment 1

[0042] In a typical implementation mode of the present invention, as Figures 1 - 8 shown, a high-pressure SCR evaporation and mixing device is proposed, including a mixing pipe 1, a first thermal insulation layer 2, a spray gun 3, and a static mixer 4. Among them, the first thermal insulation layer 2 is arranged on the outer wall of the mixing pipe 1, the static mixer 4 is detachably installed in the mixing pipe 1, the static mixer 4 includes a porous cover 4_3, and a plurality of deflectors 4_4 are fixedly arranged at intervals along the circumferential direction on the outer edge of the porous cover 4_3 for blocking the flue gas to reduce its speed and generate eddies and rotations. The spray gun 3 is detachably installed on the mixing pipe 1, the nozzle 3_3 of the spray gun 3 is located in the mixing pipe 1, and the spray gun 3 sprays in a direction away from the static mixer 4, so that the spraying direction of the spray gun 3 is the same as the flowing direction of the flue gas entering the mixing pipe 1.

[0043] As Figure 2 shown, the mixing pipe 1 is mainly composed of a pipe body 1_1, a first flange 1_2, a maintenance hole flange cover 1_3, a second thermal insulation layer 1_4, an inner cover plate 1_5, a second flange 1_6, an upper fixing seat 1_7, a lower fixing seat 1_8, and a third flange 1_9.

[0044] Among them, the pipe body 1_1 is a stainless steel round pipe structure, and a first flange 1_2 is fixedly connected to each of its two ends by welding. An inspection hole and a spray gun installation hole are provided on the side wall of the pipe body 1_1. A second flange 1_6 is installed on the inspection hole for the disassembly, position adjustment, inspection and treatment of crystallization of the static mixer 4. A third flange 1_9 is fixedly installed on the spray gun installation hole for disassembling and assembling the urea spray gun 3. A first heat insulation layer 2 is arranged on the outer wall of the pipe body 1_1, and a high-temperature resistant infrared band high-emissivity paint is sprayed after the inner wall is treated by sandblasting and pickling passivation.

[0045] Among them, the first heat insulation layer 2 is made of high-temperature resistant heat insulation material, and its inner surface is closely attached and fixed to the outer wall of the pipe body 1_1. The outer surface of the first heat insulation layer 2 is covered with galvanized low-carbon steel sheet.

[0046] A plurality of through holes are arranged on the first flange 1_2 and can be connected to the SCR connecting pipeline through bolts. A number of bolt holes are arranged on the inspection hole flange cover 1_3 and can be connected to the second flange 1_6 through bolts.

[0047] The inner cover plate 1_5 is installed in the inspection hole of the pipe body 1_1, and the second heat insulation layer 1_4 is installed between the inspection hole flange cover 1_3 and the inner cover plate 1_5 to reduce heat dissipation.

[0048] The upper fixing seat 1_7 is fixedly arranged in the inspection hole and close to the inner wall of the pipe body 1-1. A number of stud bolts 1_7_2 are fixedly arranged on the upper surface of the upper fixing seat 1_7. The inner cover plate 1_5 is provided with holes matching the stud bolts 1_7_2, and the inner cover plate 1_5 can be connected to the upper fixing seat 1_7 through the stud bolts 1_7_2.

[0049] The cross section of the upper fixing seat 1_7 is a waist-shaped hole structure same as that of the inspection hole. A number of fixing grooves 1_7_1 are also arranged on the upper surface of the upper fixing seat 1_7. The number of fixing grooves 1_7_1 are arranged oppositely and evenly along the axial direction of the upper fixing seat 1_7, mainly for fixing and adjusting the position of the static mixer 4.

[0050] The bottom surface of the lower fixing seat 1_8 is fixedly connected to the inner wall of the pipe body 1_1. The lower fixing seat 1_8 is located directly below the upper fixing seat 1_7. The axial direction of the lower fixing seat 1_8 is the same as that of the upper fixing seat 1_7. A plurality of positioning holes 1_8_1 are evenly arranged at intervals along the axial direction of the lower fixing seat 1_8 to cooperate with the fixing grooves 1_7_1 to fix and adjust the position of the static mixer 4.

[0051] The static mixer 4 is detachably installed in the pipe body 1_1 and close to the air inlet end. The static mixer 4 and the pipe body 1_1 are coaxially arranged, as Figure 8As shown, the static mixer 4 is composed of a fixed rod 4_1, an upper connecting rod 4_2, a porous cover 4_3, a flow guide vane 4_4 and a lower connecting rod 4_5. The upper connecting rod 4_2 is fixedly arranged at the top of the porous cover 4_3. The lower connecting rod 4_5 is arranged opposite to the upper connecting rod 4_2 and is fixedly arranged at the bottom of the porous cover 4_3. The fixed rod 4_1 is fixedly arranged at the top of the upper connecting rod 4_2. A number of flow guide vanes 4_4 are provided, and the number of flow guide vanes 4_4 are fixedly arranged at intervals along the circumferential direction on the outer edge of the porous cover 4_3.

[0052] Among them, the axis of the fixed rod 4_1 is perpendicular to the axis of the upper connecting rod 4_2. The fixed rod 4_1 is used to be placed in the two relatively arranged fixed grooves 1_7_1 on the upper fixed seat 1_7 to fix the position of the top of the porous cover 4_3. The lower connecting rod 4_5 is used to be inserted into the corresponding positioning hole 1_8_1 on the lower fixed seat 1_8 to fix the position of the bottom of the porous cover 4_3.

[0053] A shallow groove is milled on the upper plane of the end of the fixed rod 4_1 for installing a spring washer 4_1_1. The surfaces of the porous cover 4_3 and the flow guide vane 4_4 are sprayed with high-temperature infrared band high-emissivity paint after sandblasting and pickling passivation treatment.

[0054] The temperature of the exhaust gas flowing through the high-pressure SCR evaporation mixing device is between 550K and 770K. The mixing pipe 1 is covered with a relatively thick first heat-insulating layer 2, and the second heat-insulating layer 1_4 is filled inside the inspection hole (which can also be understood as the second flange 1_6), so that the temperature of the surface of the static mixer 4 and the inner wall of the pipeline main body 1_1 is the same as the temperature of the exhaust gas. The initial temperature of the urea solution droplets entering the mixing pipe 1 is relatively low and needs to absorb the heat of the high-temperature exhaust gas to evaporate and gasify. The heat exchange makes a low-temperature exhaust gas area formed near the urea solution injection point. The high-temperature exhaust gas outside the urea solution evaporation area will continuously flow to this low-temperature exhaust gas area. At the same time, the high-temperature exhaust gas, the surface of the static mixer 4 and the inner wall of the pipeline main body 1_1 will conduct radiative heat exchange with the low-temperature exhaust gas area.

[0055] Through the above settings, the radiative heat exchange amount between the surface of the static mixer 4 and the inner wall of the pipeline main body 1_1 and the urea solution evaporation area is increased, the temperature of the low-temperature exhaust gas area is increased, and the evaporation of the urea solution droplets can be accelerated and the gas-phase reaction can be enhanced.

[0056] It is specifically known that carbon dioxide gas has a high absorption rate in infrared thermal radiation bands such as 2.0μm, 2.7μm, 4.3μm, and 9.4μm, and water vapor has a high absorption rate in infrared thermal radiation bands such as 1.38μm, 1.87μm, 2.7μm, and 6.3μm. After the surface of the static mixer 4 and the inner wall of the pipe body 1_1 are treated by sandblasting and pickling passivation, a high-temperature resistant infrared band high-emissivity paint is sprayed; the high-temperature resistant infrared band high-emissivity paint has an emissivity of not less than 0.95 in multiple bands such as 1.38μm, 1.87μm, 2.0μm, 2.7μm, 4.3μm, 6.3μm, and 9.4μm, so that in the temperature range of 550K to 770K, most of the wall surfaces in the mixing pipe 1 are close to blackbody radiation in the above bands, strengthening the radiation heat transfer between the wall surface and the urea solution evaporation area (the urea solution contains about 60% water, which can accelerate the evaporation of water), effectively increasing the overall temperature of this area, accelerating the evaporation of urea solution droplets and enhancing the gas-phase reaction.

[0057] The diameter of the porous cover 4_3 is smaller than the inner diameter of the pipe body 1_1. The porous cover 4_3 is of a cover type structure, and a number of ventilation holes allowing the flue gas to pass through are opened on the porous cover 4_3, such as Figure 6 shown, the porous cover 4_3 protrudes towards the side away from the spray gun 3 (it can also be understood that the porous cover 4_3 protrudes towards the intake end of the pipe body 1_1).

[0058] The porous cover 4_3 and the guide vane 4_4 cooperate with each other to form a low-pressure and low-speed recirculation disturbance area near the urea solution injection point. The urea solution droplets can quickly evaporate and undergo gas-phase reactions in this area; at the same time, it is ensured that the evaporation of the droplets is limited to a narrow range, and the droplets will not form a liquid film on the surface of the static mixer 4 and the inner wall of the pipe body 1_1, and thus will not form obvious crystallized substances on the surface of the static mixer 4 and the inner wall of the mixing pipe 1_1.

[0059] Specifically, the cover type structure can block the flue gas, thereby generating a low-speed and low-pressure area behind the porous cover 4_3 (the direction after the flue gas passes through the porous cover 4_3), and several eddies (which can also be understood as vortices) will be generated in this area. The urea solution will be entrained into the vortices, and the urea solution will be more fully mixed with the flue gas here to achieve the purpose of rapid evaporation and pyrolysis;

[0060] A number of flow guiding vanes 4_4 fixedly arranged on the outer edge of the porous cover 4_3 can make the flue gas near the inner wall of the pipeline main body 1_1 rotate. The total distance traveled by the flue gas flowing backward in a spiral is longer than that of a straight forward flow, which can effectively shorten the length of the mixing pipe 1 and reduce the overall volume of the evaporation mixing device. During the spiral flow of the flue gas, part of the urea solution will also be drawn into the flue gas flowing forward in a spiral, so as to be more fully mixed in the pipeline main body 1_1, and the residence time of the droplets in the pipeline is also increased accordingly to achieve the purpose of rapid evaporation and pyrolysis.

[0061] The spray gun 3 is mainly composed of a flange 3_1, a spray gun body 3_2, and a spray head 3_3. The spray head 3_3 is installed at the end of the spray gun body 3_2, and the flange 3_1 is fixedly installed on the spray gun body 3_2. The spray gun 3 can be installed on the third flange 1_9 of the mixing pipe 1 through the flange 3_1. The urea aqueous solution is atomized into fine droplets at the spray head 3_3 and sprayed into the interior of the pipeline main body 1_1.

[0062] Embodiment 2

[0063] In another typical embodiment of the present invention, a method for using a high-pressure SCR evaporation mixing device is proposed as follows:

[0064] (1) When it is necessary to fixedly install the static mixer 4

[0065] First, insert the static mixer 4 into the pipeline main body 1_1 through the inspection hole, and insert the lower connecting rod 4_5 into the positioning hole 1_8_1 on the lower fixing seat 1_8;

[0066] Then, install the upper fixing rod 4_1 in the fixing groove 1_7_1, install the spring washer 4_1_1 in the shallow groove on the upper plane of the end of the fixing rod 4_1, and install the inner cover plate 1_5 on the stud 1_7_2 of the upper fixing seat 1_7 and tighten the bolt;

[0067] Finally, install the second thermal insulation layer 1_4 and the inspection hole flange cover 1_3.

[0068] (2) When it is necessary to disassemble the static mixer 4

[0069] First, sequentially remove the inspection hole flange cover 1_3, the second thermal insulation layer 1_4, the inner cover plate 1_5 and the spring washer 4_1_1;

[0070] Then, pull up the fixing rod 4_1 to separate the static mixer 4 from the upper fixing seat 1_7 and the lower fixing seat 1_8;

[0071] Finally, adjust the angle of the static mixer 4 and pull out the static mixer 4 as a whole from the mixing pipe 1.

[0072] (3) When it is necessary to adjust the position of the static mixer in the evaporation mixing pipeline

[0073] First, sequentially remove the inspection hole flange cover 1_3, the second insulation layer 1_4, the inner cover plate 1_5, and the spring washer 4_1_1.

[0074] Then, pull up the fixing rod 4_1 to separate the static mixer 4 from the upper fixing seat 1_7 and the lower fixing seat 1_8, and reinstall the fixing rod 4_1 and the lower connecting rod 4_5 of the static mixer 4 into the designated fixing slots 1_7_1 and positioning holes 1_8_1.

[0075] Finally, sequentially reset the spring washer 4_1_1, the inner cover plate 1_5, the second insulation layer 1_4, and the inspection hole flange cover 1_3 and tighten the bolts.

[0076] Under the stable operating state of SCR, it can effectively prevent the droplets from directly contacting the surface of the static mixer 4 and the inner wall of the mixing pipe 1, thereby effectively preventing crystallization. Under the unstable operating state of SCR, for example, when the main engine load suddenly changes and the injection amount of the urea solution and the exhaust gas flow rate cannot be immediately matched, it may cause droplet wetting of the wall, and a small amount of crystallization will occur inside the evaporation mixing pipeline. In addition, each time the SCR system stops being used, it is also necessary to purge the urea spray gun to purge the remaining urea solution into the mixing pipe 1, and a small amount of crystallization will also occur when the exhaust gas temperature is low. Therefore, after the system has been running for a long time, it is necessary to overhaul the mixing pipe 1 and deal with the crystallization. First, sequentially remove the inspection hole flange cover 1_3, the second insulation layer 1_4, and the inner cover plate 1_5. Then, inspect the static mixer 4 and the pipeline main body 1_1, replace and repair the vulnerable parts, clean the surface where crystallization appears, and if necessary, remove the spray gun 3 and use the third flange 1_9 to clean the crystallization surface. Finally, reinstall the disassembled parts.

[0077] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A high-pressure SCR evaporation mixing device, characterized in that, it includes a mixing pipe, a first heat-insulating layer arranged on the outer wall of the mixing pipe, a spray gun, and a static mixer detachably installed in the mixing pipe. The static mixer is close to the air inlet end of the mixing pipe. The static mixer contains a porous cover. Along the circumferential direction of the outer edge of the porous cover, a number of guide vanes are fixedly arranged at intervals to block the flue gas to slow down its speed and generate eddies and rotations. The porous cover protrudes towards the air inlet end of the mixing pipe. The spray gun is detachably installed on the mixing pipe, and the nozzle of the spray gun is located inside the mixing pipe. The spray gun sprays in a direction away from the static mixer and the air inlet end of the mixing pipe. High-temperature infrared band high-emissivity coatings are provided on the inner wall of the mixing pipe and the surface of the static mixer; on the inner wall of the pipe body of the mixing pipe, an upper fixing seat and a lower fixing seat are fixedly arranged. The upper fixing seat is directly above the lower fixing seat for the disassembly and installation of the static mixer. On the upper surface of the upper fixing seat, a number of relatively arranged fixing grooves are provided, and the fixing grooves are evenly arranged along the axial direction of the upper fixing seat. The axial direction of the lower fixing seat is the same as that of the upper fixing seat. Along the axial direction of the lower fixing seat, a plurality of positioning holes are evenly arranged at intervals to cooperate with the fixing grooves to fix and adjust the position of the static mixing; on the top of the porous cover, an upper connecting rod is fixedly arranged. On the upper connecting rod, a fixing rod for connecting with the upper fixing seat is fixedly arranged. The fixing rod is placed in the two relatively arranged fixing grooves on the upper fixing seat to fix the position of the top of the porous cover. On the bottom of the porous cover, a lower connecting rod connected with the lower fixing seat is fixedly arranged. The lower connecting rod is inserted into the corresponding positioning hole on the lower fixing seat to fix the position of the bottom of the porous cover.

2. A high-pressure SCR evaporation mixing device according to claim 1, characterized in that, the mixing pipe is composed of a pipe body, first flanges fixedly installed at both ends of the pipe body, a maintenance hole opened on the pipe body, and a spray gun installation hole. A second flange is fixedly installed on the maintenance hole, a third flange is installed on the spray gun installation hole, and an upper fixing seat and an inner cover plate are fixedly installed in the maintenance hole. The inner cover plate is located above the upper fixing seat.

3. A high-pressure SCR evaporation mixing device according to claim 2, characterized in that, on the upper surface of the upper fixing seat, a number of stud bolts connected with the inner cover plate are fixedly arranged. The second flange is connected with the maintenance hole flange cover, and a second heat-insulating layer is installed between the maintenance hole flange cover and the inner cover plate.

4. A high-pressure SCR evaporation mixing device according to claim 1, characterized in that, the diameter of the porous cover is smaller than the inner diameter of the mixing pipe, and a number of ventilation holes allowing the flue gas to pass through are opened on the porous cover.

5. A high-pressure SCR evaporation mixing device according to claim 1, characterized in that, on the upper plane of the end of the fixing rod, a shallow groove for installing a spring washer is provided.

6. A method for using a high-pressure SCR evaporation mixing device according to any one of claims 1-5, characterized in that, specifically as follows: Insert the static mixer into the pipe body through the maintenance hole, and insert the lower connecting rod into the positioning hole; Install the fixed rod in the fixed groove, install the spring washer in the shallow groove of the fixed rod, install the inner cover plate on the stud of the upper fixing seat and tighten the bolt. Finally, install the second heat preservation layer and the maintenance hole flange cover; When it is necessary to disassemble the static mixer, remove the maintenance hole flange cover, the second heat preservation layer, the inner cover plate and the spring washer in sequence, pull up and adjust the angle of the static mixer, and pull out the static mixer as a whole from the mixing pipe.

7. According to the method for using a high-pressure SCR evaporation mixing device described in claim 6, characterized in that, When it is necessary to adjust the position of the static mixer in the mixing pipe, remove the maintenance hole flange cover, the second heat preservation layer, the inner cover plate and the spring washer in sequence; Pull up the fixed rod to separate the static mixer from the upper fixing seat and the lower fixing seat, and reinstall the fixed rod and the lower connecting rod of the static mixer into the specified fixed groove and positioning hole; Reset the spring washer, the inner cover plate, the second heat preservation layer and the maintenance hole flange cover in sequence and tighten the bolt.

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