Urea crystal timely regeneration system and regeneration method

Abstract

The invention relates to the technical field of automobiles, in particular to a urea crystal timely regeneration system and method. The urea crystallization timely regeneration system comprises a water supply system, a water mist nozzle, a urea nozzle, a first exhaust pipe, a humidification pipe section, a mixing pipe section, an SCR box, a second exhaust pipe, a silencer and a third exhaust pipe. The first exhaust pipe, the humidifying pipe section, the mixing pipe section, the SCR box body, the second exhaust pipe, the silencer and the third exhaust pipe are communicated in sequence; the water supply system is communicated with the humidifying pipe section through a water mist nozzle; the urea nozzle is arranged on the mixing pipe section; a first pressure sensor and a first nitrogen-oxygen sensor are arranged on the upstream of the second exhaust pipe, and a first temperature sensor is arranged at the downstream end of the SCR box body. The water mist nozzle is arranged on the upstream of the urea nozzle, tail gas is humidified, urea crystals are dissolved, the problem that the urea nozzle and an exhaust pipeline are blocked is solved, crystallized urea is reused, and urea crystals are restrained from being formed again.

Description

Technical Field

[0001] The invention relates to the technical field of automobiles, and in particular to a timely regeneration system and method for urea crystals. Background Art

[0002] In order to meet the emission requirements of nitrogen oxides in emission regulations, diesel vehicles are equipped with urea systems for exhaust aftertreatment. The urea solution is pressurized and transported into the exhaust pipe, and the quality of the urea solution sprayed into the exhaust pipe is controlled by the opening of the urea nozzle. However, due to factors such as the nozzle structure and airflow, the residual urea sprayed often evaporates in the high-temperature exhaust gas or the urea solution adheres to the low-temperature exhaust pipe wall to form crystals.

[0003] After urea crystallizes in the urea nozzle and exhaust pipe of diesel vehicle exhaust, the urea nozzle cannot spray the appropriate urea solution into the exhaust according to the preset calibrated injection volume, so the nitrogen oxides in the exhaust cannot be effectively reduced, affecting emissions. If the exhaust pipe is blocked or partially blocked due to urea crystallization, it will cause the exhaust resistance to increase and the exhaust to be blocked, which will affect the engine power at the least and the engine cannot be started at the worst. Summary of the invention

[0004] The purpose of the present invention includes providing a urea crystal timely regeneration system, which can solve the above-mentioned technical problems.

[0005] The embodiments of the present invention can be implemented as follows:

[0006] In a first aspect, the present invention provides a urea crystal timely regeneration system, comprising a water supply system, a water mist nozzle, a urea nozzle, a first exhaust pipe, a humidification pipe section, a mixing pipe section, an SCR box, a second exhaust pipe, a muffler and a third exhaust pipe;

[0007] The first exhaust pipe, the humidifying pipe section, the mixing pipe section, the SCR box, the second exhaust pipe, the muffler and the third exhaust pipe are connected in sequence;

[0008] The water supply system is connected to the humidification pipe section through the water mist nozzle;

[0009] The urea nozzle is arranged on the mixing pipe section;

[0010] A first pressure sensor and a first nitrogen oxide sensor are provided at one end of the second exhaust pipe close to the SCR box, and a first temperature sensor is provided at one end of the SCR box close to the second exhaust pipe.

[0011] In an optional embodiment, an evaporation tube is provided in the humidification pipe section, and the water mist nozzle is connected to the evaporation tube;

[0012] The side wall of the evaporation tube is provided with a spray hole.

[0013] In an optional embodiment, there are multiple spray holes, and the apertures of the multiple spray holes increase sequentially in a direction away from the water mist nozzle.

[0014] In an optional embodiment, the evaporation pipe and the urea nozzle are located on the same side of the first exhaust pipe.

[0015] In an optional embodiment, the water supply system includes a water tank, a water pump and a water supply pipeline;

[0016] The water tank is connected to the water mist nozzle through the water supply pipeline, and the water pump is arranged on the water supply pipeline to transport the water in the water tank to the humidification pipe section through the water mist nozzle.

[0017] In an optional embodiment, one end of an overflow pipe is connected between the water pump and the water tank, and the other end of the overflow pipe is connected to the upper end of the water tank or the upper end of the side wall of the water tank.

[0018] In an optional embodiment, a heating device is provided between the water pump and the water mist nozzle for heating the water before entering the water mist nozzle.

[0019] In an optional embodiment, a control valve is provided between the water pump and the water tank.

[0020] In an optional embodiment, a second pressure sensor and a second nitrogen oxide sensor are provided on the first exhaust pipe.

[0021] In a second aspect, the present invention provides a timely regeneration method for urea crystals, which uses a water mist nozzle to spray the humidification pipe section to adjust the relative humidity of the exhaust gas at the front and rear ends of the SCR box, wherein the humidity upstream of the second exhaust pipe is less than the humidity downstream.

[0022] The beneficial effects of the timely regeneration system and method for urea crystallization provided by the embodiments of the present invention include:

[0023] In the exhaust pipe, a water mist nozzle is arranged upstream of the urea nozzle to humidify the exhaust gas before entering the urea mixing pipe section. The characteristic of crystalline urea that it easily absorbs moisture in gas with high humidity is utilized to dissolve urea crystals adhering to the urea nozzle and the exhaust pipe, thereby solving the problem of blockage of the urea nozzle and the exhaust pipe due to urea crystals, allowing the crystalline urea to be reused. At the same time, the humidified exhaust gas inhibits the re-formation of urea crystals. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A schematic diagram of the three-dimensional structure of a urea crystal timely regeneration system provided in an embodiment of the present invention;

[0026] Figure 2 A working principle diagram of a timely regeneration system for urea crystallization provided by an embodiment of the present invention;

[0027] Figure 3 A schematic diagram of the positions of point B and point C in a timely regeneration system for urea crystallization provided in an embodiment of the present invention;

[0028] Figure 4 A diagram showing the position relationship between a urea nozzle and a water mist nozzle in a urea crystal timely regeneration system provided in an embodiment of the present invention;

[0029] Figure 5 A schematic diagram of the structure of an evaporation tube of a urea crystal timely regeneration system provided in an embodiment of the present invention;

[0030] Figure 6 The present invention provides a flow chart of a timely regeneration method for urea crystals.

[0031] Icons: 1-water tank; 2-first water pipe; 3-control valve; 4-water pump; 5-second water pipe; 6-first exhaust pipe; 7-humidification pipe section; 8-mixing pipe section; 9-SCR box; 10-second exhaust pipe; 11-muffler; 12-third exhaust pipe; 13-first nitrogen oxide sensor; 14-first pressure sensor; 15-first temperature sensor; 16-second temperature sensor; 17-urea nozzle; 18-water mist nozzle; 19-second pressure sensor; 20-second nitrogen oxide sensor; 21-heating device; 22-overflow pipe; 23-evaporation pipe; 24-spray hole. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0035] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear to indicate an orientation or position relationship, they are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the product of the invention is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0036] In addition, the terms “first”, “second”, etc., if used, are merely used to distinguish between the descriptions and should not be understood as indicating or implying relative importance.

[0037] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0038] In a first aspect, the present invention provides a timely regeneration system for urea crystals, such as Figure 1 and Figure 2 As shown, it includes a water supply system, a water mist nozzle 18, a urea nozzle 17, a first exhaust pipe 6, a humidifying pipe section 7, a mixing pipe section 8, an SCR box 9, a second exhaust pipe 10, a muffler 11 and a third exhaust pipe 12; the first exhaust pipe 6, the humidifying pipe section 7, the mixing pipe section 8, the SCR box 9, the second exhaust pipe 10, the muffler 11 and the third exhaust pipe 12 are connected in sequence; the water supply system is connected to the humidifying pipe section 7 through the water mist nozzle 18; the urea nozzle 17 is arranged on the mixing pipe section 8; a first pressure sensor 14 and a first nitrogen oxide sensor 13 are provided at one end of the second exhaust pipe 10 close to the SCR box 9, and a first temperature sensor 15 is provided at one end of the SCR box 9 close to the second exhaust pipe 10.

[0039] In this embodiment, the water supply system sprays water mist into the humidification pipe section 7 through the water mist nozzle 18 to humidify the exhaust gas. The urea nozzle 17 is used to inject urea into the downstream of the humidification pipe section 7. The mixing pipe section 8 is a pipe section for fully mixing and hydrolyzing the urea solution and the exhaust gas. The mixing pipeline is made of a stainless steel pipe, which is arranged upstream of the SCR box 9 and welded to the front end of the SCR box 9. A hole is opened on the mixing pipe section 8 to weld a urea nozzle 17 mounting bracket for mounting the urea nozzle 17.

[0040] The first nitrogen oxide sensor 13, the first pressure sensor 14, and the first temperature sensor 15 are used to detect the nitrogen oxide content in the exhaust gas, the exhaust gas pressure and the exhaust gas temperature, respectively, and are arranged downstream of the SCR box 9 and fixed on the mounting support of the SCR box 9 or the second exhaust pipe 10 by threaded connection.

[0041] A humidifying pipe section 7 is added before the mixing pipe section 8 for installing a water mist nozzle 18. The humidifying pipe section 7 is made of a stainless steel pipe, and its cross-sectional size, ie, diameter, is larger than the first exhaust pipe 6 upstream thereof.

[0042] The tail gas before entering the urea mixing pipe section 8 is humidified, and the urea crystals adhering to the urea nozzle 17 and the exhaust pipe are dissolved by utilizing the characteristic that the crystal urea is easy to absorb moisture in the gas with high humidity, so as to solve the problem of the urea nozzle 17 and the exhaust pipe being blocked by the urea crystals, and the crystal urea is reused. At the same time, the humidified tail gas inhibits the re-formation of urea crystals.

[0043] A mounting support of the water mist nozzle 18 is welded to the side wall of the humidifying pipe section 7, and the water mist nozzle 18 and the mounting support are connected by threads.

[0044] In this embodiment, the first exhaust pipe 6, the second exhaust pipe 10 and the third exhaust pipe 12 are used to connect the components in the exhaust system. The first exhaust pipe 6 and the third exhaust pipe 12 are made of ordinary stainless steel, the second exhaust pipe 10 is made of urea-resistant stainless steel, and both ends of the second exhaust pipe 10 are connected to the exhaust post-processing and muffler 11 and other components through welding technology.

[0045] In this embodiment, a second pressure sensor 19 and a second nitrogen oxide sensor 20 are provided on the first exhaust pipe 6 .

[0046] like Figure 2 As shown, the system calculates and controls the exhaust relative humidity at points A and B according to the first nitrogen oxide sensor 13, the first pressure sensor 14, the first temperature sensor 15, the second nitrogen oxide sensor 20, the second pressure sensor 19, the second temperature sensor 16 and the ambient temperature signal. By controlling the humidity at point A so that the humidity downstream of the point is greater than 90%, the crystalline urea can absorb water and dissolve. By controlling the humidity at point B, it is ensured that no condensed water is formed in the SCR and the pipeline before the upstream of point B.

[0047] A height difference is set between point B and point C on the second exhaust pipe 10, and point B is higher than point C. Figure 3 shown.

[0048] After humidification upstream of point B, the relative humidity of the exhaust gas is high. As the exhaust pipe and components dissipate heat and cool down, the exhaust gas temperature will drop below the dew point. Combined with the temperature gradient change, the exhaust gas humidity upstream of point B is controlled to be less than 100%. The condensed water formed after the exhaust gas passes through point B can flow smoothly into the muffler 11 through the exhaust pipe 2. The height difference between point B and point C can prevent the condensed water from flowing back into the SCR box 9, so that the condensed water can quickly flow into the muffler 11 and be discharged in time through the drainage hole of the muffler 11.

[0049] In an optional embodiment, an evaporation tube 23 is provided in the humidification tube section 7 , and the water mist nozzle 18 is connected to the evaporation tube 23 ; a spray hole 24 is provided on the side wall of the evaporation tube 23 .

[0050] In this embodiment, the evaporation tube 23 is used to further heat and vaporize the high-temperature hot water sprayed from the hot water nozzle, and the vaporized water vapor flows into the exhaust gas through the small holes on the humidification tube.

[0051] Specifically, in the present embodiment, the evaporation tube 23 is made of a stainless steel tube, a small hole is punched on the tube wall as a spray hole 24, one end is connected to the water mist nozzle 18, and the other end is fixed to the inner wall of the first exhaust pipe 6. The evaporation tube 23 is connected to the inner wall of the first exhaust pipe 6 by welding, and the end of the evaporation tube 23 connected to the first exhaust pipe 6 is sealed.

[0052] In an optional embodiment, there are multiple spray holes 24 , and the apertures of the multiple spray holes 24 increase sequentially in a direction away from the water mist nozzle 18 .

[0053] The openings on the evaporation tube 23 are provided with small holes of different diameters according to the distance from the nozzle. The opening at the end closer to the nozzle is smaller, and the opening at the end farther from the nozzle is larger, so that the amount of water vapor sprayed along the evaporation tube 23 is relatively uniform.

[0054] In an optional embodiment, the evaporation pipe 23 and the urea nozzle 17 are located on the same side of the first exhaust pipe 6 .

[0055] The spray cone angle and the sprayed urea distribution of the urea nozzle 17 are arranged on the same side as the evaporation tube 23 in the mixing tube section 8. From the cross section of the exhaust pipe, the two are symmetrically distributed, as shown in FIG. Figure 4 and Figure 5 shown.

[0056] Such a configuration is conducive to the water vapor sprayed from the evaporation pipe 23 to contact with the urea nozzle 17 and the sprayed solution thereof, and flow to the area where urea crystals are easily formed, thereby more efficiently handling the urea crystallization problem.

[0057] In an optional embodiment, the water supply system includes a water tank 1, a water pump 4 and a water supply pipeline; the water tank 1 is connected to the water mist nozzle 18 through the water supply pipeline, and the water pump 4 is arranged on the water supply pipeline for transporting the water in the water tank 1 to the humidification pipe section 7 through the water mist nozzle 18.

[0058] In this embodiment, the water tank 1 is used to store humidification water. The water tank 1 is injection molded and assembled in the engine compartment. When the cabin temperature rises, the water tank 1 can be heated to solve the problem of water freezing in the water tank 1 in winter and causing it to not work normally. At the same time, the heating device 21 of the water tank 1 can be reduced to reduce the system cost.

[0059] In this embodiment, a water pump 4 is provided in the water supply system, and the water pump 4 provides power for the water circuit, overcomes the exhaust gas pressure in the exhaust pipe, and sprays water into the humidification pipe section 7 through the water mist nozzle 18.

[0060] The water supply pipeline is used to transport humidification water, and is divided into two parts, namely a first water pipe 2 and a second water pipe 5 . The first water pipe 2 and the second water pipe 5 are connected via a water pump 4 .

[0061] In an optional embodiment, one end of an overflow pipe 22 is connected between the water pump 4 and the water tank 1 , and the other end of the overflow pipe 22 is connected to the upper end of the water tank 1 or the upper end of the side wall of the water tank 1 .

[0062] In this embodiment, the overflow pipe 22 is used to remove air from the pipeline of the water spray atomization device, and after the device stops working, the residual water in the pipeline can be smoothly drained. One end of the overflow pipe 22 is connected to the first water pipe 2, between the control valve 3 and the water pump 4, and the other end is connected to the side wall above the water tank 1, and is connected to the interior of the water tank 1.

[0063] In an optional embodiment, a heating device 21 is provided between the water pump 4 and the water mist nozzle 18 for heating the water before entering the water mist nozzle 18 .

[0064] In this embodiment, a heating device 21 is provided in the downstream pipeline of the water pump 4, which is connected to the engine coolant, heats the water and then sprays it into the humidifying pipe section 7, so that the hot water is quickly vaporized into water vapor.

[0065] The heating device 21 heats the engine cooling water pipe and is formed by connecting a rubber tube and a heat exchange copper tube. The heat exchange copper tube abuts against the outer wall of the second water pipe 5 to heat the water in the second water pipe 5 .

[0066] In an optional embodiment, a control valve 3 is provided between the water pump 4 and the water tank 1 .

[0067] In this embodiment, the control valve 3 is used to control the on-off of the humidification pipeline. The control valve 3 controls the opening and closing of the pipeline according to system instructions through a controller and is installed on the first water pipe 2.

[0068] In this embodiment, a control valve 3 is provided between the water pump 4 and the water tank 1. When the system is working, the control valve 3 is opened, and water flows into the pipeline through the control valve 3; before the humidification system stops working, the control valve 3 is closed, and the water in the water pipe downstream of the control valve 3 is drained to prevent the water pipe from freezing and bursting in winter.

[0069] In a second aspect, the present invention provides a timely regeneration method for urea crystals, wherein a water mist nozzle 18 is used to spray the humidification pipe section 7 to adjust the relative humidity of the exhaust gas at the front and rear ends of the SCR box 9, wherein the humidity upstream of the second exhaust pipe 10 is less than the humidity downstream.

[0070] Specifically, Figure 6 As shown, in this embodiment, the air moisture content is calculated by the cabin ambient temperature and the cabin ambient humidity, the intake air moisture flow is calculated by the intake air flow, and then the exhaust water flow before point P is obtained by combining the water mass generated by combustion in the cylinder per unit time, and the exhaust water flow before point A is obtained by combining the remaining water amount of the injected urea solution and the water mass added by the water mist nozzle 18 in the cylinder per unit time;

[0071] The mass flow rate of the combustion gas per unit time is obtained by the intake air flow rate, and the relative humidity of the exhaust gas at point B is obtained by combining the exhaust pressure and exhaust temperature at point B and the water content flow rate of the exhaust gas before point A obtained previously;

[0072] The relative humidity of the exhaust gas at point A is obtained by the exhaust pressure at point A, the exhaust temperature, the gas flow mass generated by the combustion in the cylinder per unit time, and the water content flow of the exhaust gas before point A obtained previously;

[0073] The humidity of points B and C is judged according to the relative humidity of the exhaust gas at point A and point B: when the humidity at point B is greater than 90% and the humidity at point C is greater than 98%, the water mist nozzle 18 is closed and no humidification is required; when the humidity at point B is less than or equal to 90% and the humidity at point C is less than or equal to 98%, the amount of water required to humidify point B to 90% and the amount of water required to humidify point C to 98% are calculated, and the calculated water addition amounts at points B and C are compared. The smaller value is the water addition amount of the water mist nozzle 18. At this time, it is judged whether the pressure difference between points A and C is greater than the set value, or whether the running mileage is greater than the set value: when it is greater than the set value, the water mist nozzle 18 is turned on to humidify the exhaust gas according to the required water addition amount; when the set working time is reached, the water mist nozzle 18 is closed.

[0074] like Figure 2 As shown, the system calculates and controls the relative humidity of the exhaust gas at points A and B according to the nitrogen oxide sensor, pressure sensor, temperature sensor and ambient temperature signals. By controlling the humidity at point A so that the humidity downstream of this point is greater than 90%, the crystalline urea can absorb water and dissolve. By controlling the humidity at point B, it ensures that no condensed water is formed in the SCR and pipeline upstream of point B.

[0075] Specifically, the calculation method of the water vapor mass flow rate at point A is as follows:

[0076] M A =M1+M2+M3

[0077] Among them, M A is the water vapor mass flow rate at point A;

[0078] M1 is the mass of water vapor in the engine intake air per unit time;

[0079] M2 is the amount of water vapor produced by engine combustion per unit time;

[0080] M3 is the mass of water vapor added to the humidification system per unit time.

[0081] A height difference is set between point B and point C on the second exhaust pipe 10, and point B is higher than point C. Figure 3 shown.

[0082] After humidification upstream of point B, the relative humidity of the exhaust gas is high. As the exhaust pipe and components dissipate heat and cool down, the exhaust gas temperature will drop below the dew point. Combined with the temperature gradient change, the exhaust gas humidity upstream of point B is controlled to be less than 100%. The condensed water formed after the exhaust gas passes through point B can flow smoothly into the muffler 11 through the exhaust pipe 2. The height difference between point B and point C can prevent the condensed water from flowing back into the SCR box 9, so that the condensed water can quickly flow into the muffler 11 and be discharged in time through the drainage hole of the muffler 11.

[0083] The beneficial effects of the timely regeneration system and method for urea crystallization provided by the embodiments of the present invention include:

[0084] In the exhaust pipe, a water mist nozzle 18 is arranged upstream of the urea nozzle 17 to humidify the exhaust gas before entering the urea mixing pipe section 8. The characteristic of crystalline urea being easy to absorb moisture in gas with high humidity is utilized to dissolve the urea crystals adhering to the urea nozzle 17 and the exhaust pipe, thereby solving the problem of blockage of the urea nozzle 17 and the exhaust pipe due to urea crystals, so that the crystalline urea can be reused. At the same time, the humidified exhaust gas inhibits the re-formation of urea crystals; timely regeneration, regular regeneration and fixed mileage regeneration are performed, and the user does not need to manually set the regeneration, thereby ensuring the timely regeneration of the post-processed urea crystals without affecting the user's use.

[0085] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A urea crystal timely regeneration system, characterized in that: It includes a water supply system, a water mist nozzle, a urea nozzle, a first exhaust pipe, a humidifying pipe section, a mixing pipe section, an SCR box, a second exhaust pipe, a muffler and a third exhaust pipe; The first exhaust pipe, the humidifying pipe section, the mixing pipe section, the SCR box, the second exhaust pipe, the muffler and the third exhaust pipe are connected in sequence; The water supply system is connected to the humidification pipe section through the water mist nozzle; The urea nozzle is arranged on the mixing pipe section; A first pressure sensor and a first nitrogen oxide sensor are provided at one end of the second exhaust pipe close to the SCR box, and a first temperature sensor is provided at one end of the SCR box close to the second exhaust pipe.

2. The urea crystal timely regeneration system according to claim 1, characterized in that: An evaporation tube is provided in the humidification pipe section, and the water mist nozzle is connected to the evaporation tube; The side wall of the evaporation tube is provided with a spray hole.

3. The urea crystal timely regeneration system according to claim 2, characterized in that: There are multiple spray holes, and the diameters of the multiple spray holes increase sequentially in a direction away from the water mist nozzle.

4. The urea crystal timely regeneration system according to claim 2, characterized in that: The evaporation pipe and the urea nozzle are located on the same side of the first exhaust pipe.

5. The urea crystal timely regeneration system according to claim 1, characterized in that: The water supply system includes a water tank, a water pump and a water supply pipeline; The water tank is connected to the water mist nozzle through the water supply pipeline, and the water pump is arranged on the water supply pipeline to transport the water in the water tank to the humidification pipe section through the water mist nozzle.

6. The urea crystal timely regeneration system according to claim 5, characterized in that: One end of an overflow pipe is connected between the water pump and the water tank, and the other end of the overflow pipe is connected to the upper end of the water tank or the upper end of the side wall of the water tank.

7. The urea crystal timely regeneration system according to claim 5, characterized in that: A heating device is provided between the water pump and the water mist nozzle, for heating the water before entering the water mist nozzle.

8. The urea crystal timely regeneration system according to claim 5, characterized in that: A control valve is provided between the water pump and the water tank.

9. The urea crystal timely regeneration system according to claim 1, characterized in that: The first exhaust pipe is provided with a second pressure sensor and a second nitrogen oxide sensor.

10. A method for timely regeneration of urea crystals, characterized in that: The relative humidity of the exhaust gas at the front and rear ends of the SCR box is adjusted by spraying the humidification pipe section with a water mist nozzle, wherein the humidity at the upstream of the second exhaust pipe is less than the humidity at the downstream.

Images