Urea decomposition device with cyclonic particulate collector

Abstract

The application discloses a urea decomposition device with a cyclone particle collector, which comprises a cyclone particle collector and a controller, wherein the cyclone particle collector comprises a cyclone cylinder, a particle collection barrel arranged at the lower end of the cyclone cylinder, a heating and sensing unit arranged in the particle collection barrel, and an air outlet pipe arranged at the upper end of the cyclone cylinder; tail gas and urea droplets enter the cyclone cylinder, a rotating air flow is formed in the cyclone cylinder, urea solution is decomposed along with the air flow, unreacted large-particle urea droplets are separated from the main air flow and then flow into the particle collection barrel, and a mixture of small-particle urea droplets, ammonia gas and tail gas generated by decomposition flows out through the air outlet pipe; the heating and sensing unit is electrically connected with the controller and is used for detecting the amount of urea flowing into the particle collection barrel and heating and removing urea accumulated in the particle collection barrel. The application reduces energy consumption, improves the effectiveness of urea decomposition, and reduces the influence of sulfur on downstream catalysts.

Description

Technical Field

[0001] This invention relates to a urea decomposition device, and more particularly to a urea decomposition device with a cyclone particle collector. Background Technology

[0002] To remove nitrogen oxides (NOx) from engine exhaust, selective catalytic reduction (SCR) technology is generally used, utilizing the reaction between a reducing agent and NOx to remove them. Typically, an SCR system comprises five parts: a catalyst assembly, a sensor module, a controller unit, a reducing agent storage device, and a reducing agent metering injection device. The catalyst assembly includes catalyst encapsulation, exhaust piping, and a urea decomposition device; the sensor module generally includes an exhaust temperature sensor and a NOx sensor; the controller unit can be a standalone catalytic reduction system controller (DCU) or integrated with the engine control unit (ECU); the reducing agent storage device stores and prepares the reducing agent, typically including a reducing agent heating device, a reducing agent level sensor, a reducing agent temperature sensor, and a reducing agent quality sensor; the reducing agent metering injection device precisely injects the reducing agent or reducing agent carrier into the exhaust gas at a specific dosage, mixing it with the exhaust gas. The uniformly mixed exhaust gas reacts on the catalyst surface, thereby removing NOx. Currently, the most widely used SCR system in practical applications is the one using ammonia as a reducing agent. To ensure safe storage and use, as well as accurate metering, urea solution is used as a carrier for the ammonia reducing agent. In such a system, the reducing agent metering injection device injects urea solution into the exhaust gas. Under the action of the high-temperature exhaust gas, urea undergoes pyrolysis and hydrolysis to produce ammonia, which then reacts with nitrogen oxides. This type of reducing agent metering injection device is also called an automotive urea metering injection device, or simply a urea metering injection device.

[0003] There are two main injection methods for urea metering and injection devices. One is the airless method, in which the urea metering and injection system includes a urea pump and a urea nozzle. The urea pump pressurizes the urea solution and injects it into the exhaust gas flow of the SCR system through the urea nozzle. The flow rate of the urea solution is controlled by the on / off state of the urea nozzle. The commonly used control method is pulse width modulation (PWM), which controls the urea solution injection flow rate by adjusting the nozzle opening time within a repetitive fixed cycle. The other method is the air-assisted method. In this method, the urea solution is first metered by the urea pump or other urea metering device, and then mixed with compressed air. The resulting gas-liquid mixture enters the exhaust gas flow.

[0004] Compared to air-assisted injection, airless injection does not introduce compressed air, thus preserving exhaust gas energy and enabling more efficient hydrolysis and pyrolysis of urea. Furthermore, the metering method of airless injection can reduce the impact of pressure fluctuations and other factors through compensation (adjusting the PWM pulse width), resulting in high injection accuracy and better adaptability to increasingly stringent OBD requirements. These advantages of airless injection have led to its increasingly widespread application.

[0005] However, due to limitations in injection pressure, the atomized particle size of airless injection is larger compared to air-assisted injection. Larger urea droplets are less likely to mix evenly with the exhaust gas flow and also hinder the hydrolysis and pyrolysis of urea. Uneven mixing of urea droplets reduces SCR reaction efficiency, while incompletely hydrolyzed and pyrolyzed urea droplets can crystallize in the SCR system, potentially clogging the exhaust pipe. To address these issues, airless injection systems typically use a mixer in conjunction with the urea nozzle to further pulverize the urea particles and achieve more uniform mixing.

[0006] However, the mixer itself obstructs the exhaust gas flow, increasing engine back pressure and thus fuel consumption. Generally, the better the mixing effect and the less crystallization, the more complex the mixer structure and the greater its impact on engine back pressure. Simultaneously, to enhance hydrolysis and pyrolysis in the low-temperature exhaust gas to reduce crystallization and improve SCR reaction efficiency under low-temperature conditions, the low-temperature exhaust gas also needs to be heated. Since the exhaust gas flow rate is much greater than the urea solution flow rate, heating the exhaust gas to improve urea decomposition is highly uneconomical.

[0007] In addition, sulfides are a common impurity in engine fuel. The combustion of sulfides produces gaseous sulfur oxides (mainly sulfur dioxide) and sulfur-containing particulate matter. These sulfur-containing substances can poison certain SCR catalysts, such as copper-based molecular sieve SCR catalysts, and in severe cases, cause catalyst deactivation. Heating the catalyst can largely restore its activity (this process is also called desulfurization regeneration), but frequent desulfurization regeneration leads to increased engine fuel consumption and reduces the lifespan of the catalyst and aftertreatment system.

[0008] Therefore, it is urgent to solve the above problems. Summary of the Invention

[0009] Purpose of the invention: The purpose of this invention is to provide a urea decomposition device that improves the efficiency of urea decomposition while reducing energy consumption and reducing the impact of sulfur on downstream catalysts.

[0010] Technical Solution: To achieve the above objectives, this invention discloses a urea decomposition device with a cyclone particulate collector, comprising a cyclone particulate collector and a controller. The cyclone particulate collector includes a cyclone cylinder, a particle collection bucket located at the lower end of the cyclone cylinder, a heating sensing unit arranged in the particle collection bucket, and an airflow outlet pipe located at the upper end of the cyclone cylinder. Exhaust gas and urea droplets enter the cyclone cylinder, forming a rotating airflow within it. The urea solution decomposes along with the airflow, and unreacted large urea droplets separate from the main airflow and then flow into the particle collection bucket. The mixture of small urea droplets, ammonia produced during decomposition, and exhaust gas flows out through the airflow outlet pipe. The heating sensing unit is electrically connected to the controller and is used to detect the amount of urea flowing into the particle collection bucket and to heat and remove urea accumulated in the particle collection bucket.

[0011] The heating sensing unit includes a particle quantity sensor for detecting particulate matter and a heating device for heating urea. Both the particle quantity sensor and the heating device are electrically connected to the controller.

[0012] Furthermore, the upper surface of the heating device is coated with a catalyst coating that comes into contact with the urea flowing into the particle collection tank.

[0013] Furthermore, the heating device is equipped with a heating unit, which includes a heat conductor and an electric heating element. The electric heating element is electrically connected to and controlled by the controller.

[0014] Preferably, the particle quantity sensor includes two particle quantity detection electrodes, and the controller includes a reactance measurement circuit for measuring the impedance change between the two particle quantity detection electrodes.

[0015] Preferably, the controller controls the heating unit based on the impedance change measured by the reactance measurement circuit. The impedance value Zs detected by the two particle quantity detection electrodes is transmitted to the controller, and the exhaust gas temperature value T161 of the cyclone particulate collector is transmitted to the controller. The controller compares the impedance value Zs with the threshold Thd_PLL. When the impedance value Zs is greater than the threshold Thd_PLL, it compares the exhaust gas temperature value T161 with the threshold Thd_STL. When T161 is less than Thd_STL, it outputs a start control signal for the heating unit. When T161 is not less than Thd_STL, it compares the temperature value T161 with another threshold Thd_STH. When T161 is greater than Thd_STH, it outputs a shut-off control signal for the heating unit. When the impedance value Zs is not greater than the threshold Thd_PLL, it outputs a shut-off control signal for the heating unit and a maintenance signal.

[0016] Furthermore, the controller generates a maintenance signal based on the impedance change measured by the reactance measurement circuit, reminding the user to clean the particle collection bucket. The impedance value Zs detected by the two particle quantity detection electrodes is transmitted to the controller. The controller compares the impedance value Zs with the threshold Thd_PLL. When the impedance value Zs is not greater than the threshold Thd_PLL, the controller outputs a maintenance signal.

[0017] Furthermore, it also includes a brake kinetic energy recovery device electrically connected to the controller, which includes a transmission device connected to the wheel and a kinetic energy to electrical energy conversion device connected to the transmission device; the controller uses the electrical energy generated by the brake kinetic energy recovery device to control the heating unit.

[0018] Preferably, the inner wall of the cyclone cylinder is coated with a catalyst coating structure, which includes a catalyst coating for urea hydrolysis.

[0019] Furthermore, the particle collection tank contains a collecting substance for sulfate and sulfite ions, which reacts with compounds containing sulfate and sulfite ions to form salts.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The present invention does not only crush urea droplets by collision with the mixer, but also separates urea droplet particles, collecting large particles only through small particles and then heating and decomposing them; since only a portion of the urea is heated without decomposing large particles, rather than heating all urea particles, and not heating the exhaust gas, the heating power can be greatly reduced, reducing energy consumption, and the heating effectiveness and urea decomposition effectiveness can also be greatly improved; in addition, the present invention can collect and solidify sulfur to reduce sulfur-containing compounds entering the catalyst, thereby avoiding frequent desulfurization regeneration of the catalyst. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention;

[0022] Figure 2 This is a front view of the cyclone particle collector in this invention;

[0023] Figure 3 This is a top view of the cyclone particle collector in this invention;

[0024] Figure 4 This is a schematic diagram of the inverted conical cyclone cylinder in this invention;

[0025] Figure 5 This is a schematic diagram of the heating sensing unit in this invention;

[0026] Figure 6 This is a top view of the heating sensing unit in this invention;

[0027] Figure 7 This is a schematic diagram of the heating unit in this invention;

[0028] Figure 8 This is a schematic diagram of the controller controlling the heating unit in this invention;

[0029] Figure 9 This is a schematic diagram of the exhaust temperature and electric heating control signals in this invention;

[0030] Figure 10 This is a schematic diagram of the brake energy recovery device in this invention. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0032] like Figure 1 As shown, this invention is a urea decomposition device applied to an SCR system, used to decompose automotive urea injected into exhaust gas. The SCR system includes a controller 140 and an airflow inlet pipe 101, a urea nozzle 102, a decomposition pipe 103, a mixer 104, a cyclone particulate collector 100, an airflow outlet pipe 111, an SCR catalyst 160, an upper exhaust temperature sensor 161, a lower exhaust temperature sensor 162, and piping 112 arranged along the exhaust gas flow direction. Exhaust gas generated by the engine enters the cyclone particulate collector (CPC) 100 through the airflow inlet pipe 101, the decomposition pipe 103, and the mixer 104. A urea nozzle 102 is installed on the decomposition pipe 103, through which urea solution is injected into the exhaust gas flow. The urea nozzle 102 can be an electronically controlled nozzle, which includes a solenoid valve for controlling the nozzle's on / off state. This solenoid valve can be controlled by the controller 140 via signal line 181. By controlling the opening time of the electronically controlled nozzle within a repetitive cycle, the flow rate of the urea solution flowing through the nozzle can be controlled (using pulse width modulation or PWM methods). Furthermore, controlling the flow rate of the urea solution can further control the urea solution content (ammonia-to-nitrogen ratio) in the exhaust gas. The mixer 104 further reduces the size of the urea solution droplets through collision, while simultaneously ensuring a more uniform mixing of the urea droplets with the exhaust gas flow.

[0033] like Figure 2 and Figure 3As shown, CPC100, along with its connected upstream decomposition pipe 103, airflow inlet pipe 101, and airflow outlet pipe 111, as well as a urea nozzle 102 on the decomposition pipe 103 and a mixer 104 within the decomposition pipe 103, are included. The cyclone particle collector 100 includes an inverted conical cyclone cylinder 110, a particle collection bucket 115, and a heating sensing unit 116. The particle collection bucket 115 is located at the lower end of the inverted conical cyclone cylinder 110 and contains a collecting substance containing sulfate and sulfite ions. This collecting substance reacts with compounds containing sulfate and sulfite ions to form salts. The heating sensing unit 116 is located at the bottom of the particle collection bucket 115 and includes a particle quantity sensor and a heating device. The particle quantity sensor is electrically connected to a controller 140 via signal line 189, and the heating device is electrically connected to the controller 140 via signal line 182. The particle size sensor detects the amount of particulate matter in the CPC, while the heating device heats the particulate matter to pyrolyze and hydrolyze the urea component. After passing through CPC100, the exhaust gas enters the SCR catalyst 160 through the gas outlet pipe 111. In the SCR catalyst, ammonia obtained from the hydrolysis and pyrolysis of urea reacts with nitrogen oxides in the exhaust gas to generate nitrogen and water, thus removing them. The purified exhaust gas flows out of the system through pipe 112. An upper exhaust temperature sensor 161 is installed on the gas outlet pipe 111. This upper exhaust temperature sensor transmits the upstream exhaust temperature detection signal of the SCR to the controller 140 through signal line 183. The downstream exhaust temperature information of the SCR is transmitted to the controller 140 by the lower exhaust temperature sensor 162 installed on pipe 112 through signal line 184. The mixture of exhaust gas and urea droplets collides and breaks into small droplet particles after passing through the mixer 104, and then enters the cyclone cylinder 110, where a rotating airflow is formed. Under centrifugal force, the droplets move outward, with smaller particles moving towards the interior and larger particles towards the exterior. The particles separate from the main airflow and move closer to the barrel wall, with larger particles moving closer to the edge. Under gravity, larger particles collide with the barrel wall of the cyclone cylinder 110 and fall along its conical structure into the particle collection barrel 115, with most adhering to the heating sensing unit 116. The particle quantity sensor on the heating sensing unit 116 is electrically connected to the controller 140 via signal line 189, and the heating device is connected to the controller 140 via signal line 182. The inverted conical cyclone cylinder 110 has an inverted conical structure with openings at both the top and bottom, and a larger upper end and a smaller lower end. In the CPC 100, large urea droplets separate from the main exhaust gas flow and are then collected and concentrated for heating and decomposition. Since there is no strong airflow in the particle collection barrel, the heating energy is mainly used to decompose urea rather than heat the exhaust gas, resulting in relatively low heating power and energy consumption.

[0034] To reduce the likelihood of urea droplets colliding with the cyclone separator wall under low discharge temperatures and forming crystals, a urea decomposition catalyst (hydrolysis catalyst) can be coated onto the separator wall. The cyclone separator can be made of materials such as stainless steel, while the urea decomposition catalyst can be a metal oxide catalyst (such as titanium dioxide TiO2 or zirconium dioxide ZrO2). In CPC (Cyclone Processing), large urea particles collide with the cyclone separator wall. The catalyst coating on the cyclone separator wall prevents crystallization. Furthermore, the cyclone separator wall has a conical structure extending downwards, ensuring that fallen particles enter the particle collection bin instead of adhering to the wall. Many technologies can be used to fix the catalyst coating on the cyclone separator wall, such as... Figure 4 In one embodiment shown, the inner wall of the cyclone cylinder 110 has a catalyst coating structure 142, which includes a well-shaped structure 143 formed by corrosion and a catalyst coating 144. The well-shaped structure 143 can better bond and secure the catalyst coating 144.

[0035] One embodiment of the heating sensing unit 116 is as follows: Figure 5 , Figure 6 and Figure 7 As shown. In this embodiment, the heating sensing unit 116 includes a housing 410, a lower base 430, an upper base 431, a bolt 411, a heating unit 420, a heat-conducting column 418, a catalyst coating 419, calcium carbonate particles 429, a particle quantity detection electrode one 415, and a particle quantity detection electrode two 416. Figure 5 , Figure 6 and Figure 7As shown, the lower base 430 and the upper base 431 are fastened to the outer casing 410 with bolts 411. Corresponding grooves that form a closed space are provided on the upper surface of the lower base 430 and the lower surface of the upper base 431. A heating unit 420 is located within the closed space between the lower base 430 and the upper base 431. The heating unit 420 consists of a heat conductor 441 and an electric heating element 442. The electric heating element 442 has an electrode 426 and an electrode 427. Electrodes 426 and 427 are provided with an outer insulator 425 and an outer insulator 428 to insulate them from the upper and lower bases 431 and 430. Electrodes 426 and 427 are electrically connected to the controller 140 via a signal line 182. A heat-conducting pillar 418 is located on the upper base 431, and a catalyst coating 419 is applied to the outer surfaces of the upper base 431 and the heat-conducting pillar 418. To solidify sulfur-containing compounds to protect the SCR, porous calcium carbonate particles 429 can be placed on the upper base 431. Particle quantity detection electrode one 415 and particle quantity detection electrode two 416 are inserted in the middle of the upper base 431 and lower base 430. The bottom of particle quantity detection electrode one 415 is provided with an outer insulator three 421 to insulate it from the upper and lower bases 431 and 430, while the electrode part is in contact with the particles. The bottom of particle quantity detection electrode two 416 is provided with an outer insulator four 423, and its lower electrode part is also covered with an outer insulator 417, so only the upper electrode is in contact with the particles. Particle quantity detection electrodes one 415 and particle quantity detection electrode two 416 are connected to the controller 140 via signal line 189.

[0036] Under high-sulfur oil conditions, sulfur oxides (mainly gaseous sulfur dioxide and sulfur-containing particulate matter) are present in the exhaust gas. These sulfur oxides, when entering the SCR (Self-Catalyst Catalyst), can cause catalyst deactivation (catalyst poisoning). Sulfur oxides form sulfate and sulfite ions in the urea solution droplets. These ions can be solidified by adding a collecting material to the particulate collection tank 115. A commonly used collecting material is calcium carbonate, which reacts with the sulfate and sulfite ions in the urea droplets flowing into the particulate collection tank to form calcium sulfate. During maintenance, the cyclone separator and particulate collection tank can be desulfurized to restore catalyst efficiency, and the calcium carbonate particles can be replaced. In this way, the CPC (Catalyst Processing Unit) can effectively filter sulfur, thus protecting the SCR catalyst. Furthermore, the exhaust gas after passing through the CPC is thoroughly mixed (the flow path is longer), and the temperature and nitrogen oxide measurements can better reflect average values ​​(no sampling mixer is required).

[0037] exist Figure 5 , Figure 6 and Figure 7In the structure shown, the upper part of particle quantity detection electrode 2 416 is covered by an insulating layer 417. When the particle accumulation height exceeds the outer insulating layer, the impedance between particle quantity detection electrode 1 415 and particle quantity detection electrode 2 416 will change. By detecting this impedance change, it is possible to detect whether the particle quantity exceeds the limit. When the controller 140 detects that the particle quantity exceeds the limit, it will trigger a maintenance signal to prompt and request the user to perform maintenance on CPC 100.

[0038] During the maintenance of CPC 100, first shut down the engine. Then, after CPC 100 has cooled down, remove the particle collection tank 115 from the inverted conical cyclone cylinder 110 and clean out the collected material. After cleaning, further cleaning can be performed using a cleaning solution containing a weak acid, followed by drying and replacing the calcium carbonate particles. After maintenance, reinstall the particle collection tank 115 back into the system.

[0039] Particle quantity detection electrodes 415 and 416 detect the impedance value Zs and the temperature value T161 measured by the upper exhaust temperature sensor, which are then transmitted to the controller. The controller uses these impedance and temperature values ​​to control the heating unit, causing the urea in the particle collection tank to hydrolyze and pyrolyze into ammonia, and generating a maintenance signal to remind the user to clean the particle collection tank. The controller compares the impedance value Zs with a threshold Thd_PLL. When the impedance value Zs is greater than the threshold Thd_PLL, it compares the temperature value T161 with another threshold Thd_STL. When T161 is less than Thd_STL, it outputs a start control signal for the heating unit. When T161 is not less than Thd_STL, it compares the temperature value T161 with another threshold Thd_STH. When T161 is greater than Thd_STH, it outputs a stop control signal for the heating unit. When the impedance value Zs is not greater than the threshold Thd_PLL, it outputs a stop control signal for the heating unit and also outputs a maintenance signal. In the CPC (Cyclic Purification Process), the electric heating function raises the temperature of the collected urea droplets, causing them to hydrolyze and pyrolyze into ammonia. The generation of electric heating and maintenance signals for the heating unit can be controlled by a program running in controller 140. A flowchart of a routine is shown below. Figure 8As shown, this routine is an interrupt service routine with an interrupt cycle of T. After the program starts, it first compares the impedance value Zs (the magnitude of the impedance) measured by electrodes 415 and 416 with the threshold Thd_PLL. When Zs is greater than this threshold, it compares the temperature value T161 measured by the upper temperature sensor 161 with the threshold Thd_STL. When T161 is less than Thd_STL, the heater control signal HTC is set to 1, electric heating is turned on, and then the program ends. If T161 is not less than Thd_STL, then T161 is compared with another threshold Thd_STH. When T161 is greater than Thd_STH, HTC is set to 0, electric heating is turned off; otherwise, the original HTC state is maintained. The program ends after completing this step. It then returns to the comparison of Zs and Thd_PLL. If Zs is not greater than Thd_PLL, the particulate matter collection amount exceeds the limit. In this case, HTC is set to 0, and then a flag bit F_PL is set to 1. The F_PL flag will trigger an alarm signal (such as an indicator light) to remind the user that the system needs maintenance.

[0040] In such Figure 8 Under the control of the example program, the electric heating control signal changes with the exhaust temperature value T161 as shown in the curve. Figure 6 As shown. Figure 9 In the diagram, curve 301 represents the exhaust gas temperature change curve, and curve 302 represents the HTC signal. When the exhaust gas temperature T161 is lower than THD_STL, the electric heater is activated; when it exceeds THD_STL, the electric heater is deactivated.

[0041] Figure 5 In this process, the electric heating energy for the heating sensing unit 116 can be provided by brake recovery energy. For frequent start-stop conditions, the exhaust gas temperature is low, resulting in more liquid droplet particles being collected. The braking energy is also greater, leading to frequent heating, which helps eliminate liquid droplet particles. For example... Figure 10 As shown, in one example, the brake energy recovery device includes a drive control unit 152 and a motor generator 155 mounted on axle 153. Axle 153 is connected to wheel 154, and motor generator 155 is electrically connected to control unit 140 via signal line (wire group) 151. When the vehicle brakes, motor generator 155 enters generator mode and is driven by axle 153. The electricity generated by motor generator 155 is applied to heating sensor unit 116 via signal line 151, controller 140, and signal line 182 for heating.

[0042] The heating time of the heating sensing unit 116 is related to the exhaust temperature and flow rate. Lower exhaust temperatures and smaller flow rates result in larger droplet particles due to insufficient energy for evaporating the urea solution and hydrolyzing and pyrolyzing the urea. This increases the amount of droplets falling into the collection bucket 115, and the increased droplet flow requires more heating energy to remove them. During vehicle operation, low exhaust temperatures and low exhaust flow rates are often caused by frequent starts and stops. Frequent starts and stops increase battery consumption (especially when charging power is low). If too much energy is used for heating, it will affect battery storage. Using braking energy for heating can fully utilize the increased braking energy recovery during frequent starts and stops, balancing the heating energy consumption. (The more frequent the braking, the more braking energy is recovered, resulting in more heating energy and a greater ability to remove droplet particles). Furthermore, brake heating is an energy recovery process and does not increase fuel consumption.

[0043] The working process of this invention is as follows: First, urea droplets ejected from the urea nozzle 102 collide with the mixer 104, breaking into small droplet particles. These small droplet particles, along with the airflow, then enter the cyclone cylinder 110 of the CPC 100 and rotate rapidly. Under centrifugal force, the droplet particles move outwards, with smaller particles moving towards the interior and larger particles towards the exterior. These larger particles collide with the wall of the cyclone cylinder 110 and fall along its conical structure. The cyclone cylinder wall is coated with a urea hydrolysis catalyst. The urea droplet particles undergo hydrolysis and pyrolysis simultaneously during their movement, and the particles colliding with the cyclone cylinder 110 are accelerated in this process by the catalyst on its surface. Unreacted large droplet particles flow into the collection tank 115. A heating sensing unit 116 is located at the bottom of the collection tank 115. When the particle size sensor detects a certain amount of deposit, it activates electric heating to heat the urea particle deposits, causing hydrolysis and electrolysis (the heater is equipped with a catalyst). Electric heating can also be activated at a certain exhaust temperature to help the urea particles decompose rapidly. Porous calcium carbonate particles can also be arranged on the heater to adsorb sulfur dioxide and sulfur trioxide (the combustion of high-sulfur oil produces sulfur dioxide and sulfur trioxide; these products react with water, urea, and ammonia in the urea solution to produce sulfuric acid and sulfite ions, which then react with calcium carbonate to form calcium sulfate), thus protecting the SCR from sulfur poisoning. When the particle size sensor detects that the accumulated particle amount exceeds a certain value, it sends a maintenance request signal. At this time, unit 116 needs to be removed, non-decomposable components cleaned (e.g., using a weak acid for cleaning), and the calcium carbonate particles replaced. The exhaust gas, after filtering out large urea droplets, flows out through the exhaust outlet pipe 111.

Claims

1. A urea decomposition device with a cyclone particle collector, characterized in that: The system includes a cyclone particulate collector and a controller. The cyclone particulate collector comprises a cyclone cylinder, a particulate collection bucket located at the lower end of the cyclone cylinder, a heating and sensing unit arranged in the particulate collection bucket, and an airflow outlet pipe located at the upper end of the cyclone cylinder. Exhaust gas and urea droplets enter the cyclone cylinder, forming a rotating airflow within it. The urea solution decomposes along with the airflow, and unreacted large urea droplets separate from the main airflow and then flow into the particulate collection bucket. Small urea droplets, a mixture of decomposition-generated ammonia and exhaust gas, flow out through the airflow outlet pipe. The heating and sensing unit... The heating sensing unit is electrically connected to the controller and is used to detect the amount of urea flowing into the particle collection tank and to remove urea accumulated in the particle collection tank by heating. The heating sensing unit includes a particle quantity sensor for detecting the amount of particulate matter and a heating device for heating the urea. Both the particle quantity sensor and the heating device are electrically connected to the controller. The heating device contains a heating unit, which includes a heat conductor and an electric heating element. The electric heating element is electrically connected to and controlled by the controller. The particle quantity sensor includes two particle quantity detection electrodes. The controller includes a reactance measurement circuit for measuring the impedance change between two particle quantity detection electrodes. The controller controls the heating unit based on the impedance change measured by the reactance measurement circuit. The impedance value Zs measured by the reactance measurement circuit is transmitted to the controller. The exhaust gas temperature value T161 of the cyclone particle collector is also transmitted to the controller. The controller compares the impedance value Zs with a threshold Thd_PLL. When the impedance value Zs is greater than the threshold Thd_PLL, it compares the exhaust gas temperature value T161 with a threshold Thd_STL. When T161 is less than Thd_STL, it outputs a start control signal to the heating unit. When T161 is not less than Thd_STL, it compares the temperature value T161 with another threshold Thd_STH. When T161 is greater than Thd_STH, it outputs a shut-off control signal to the heating unit. When the impedance value Zs is not greater than the threshold Thd_PLL, it outputs a shut-off control signal to the heating unit. The controller generates a maintenance signal based on the impedance change measured by the reactance measurement circuit to remind the user to clean the particle collection tank. The impedance value Zs measured by the reactance measurement circuit is transmitted to the controller. The controller compares the impedance value Zs with the threshold Thd_PLL. When the impedance value Zs is not greater than the threshold Thd_PLL, the maintenance signal is generated.

2. The urea decomposition device with a cyclone particle collector according to claim 1, characterized in that: The upper surface of the heating device is coated with a catalyst coating that comes into contact with the urea flowing into the particle collection tank.

3. The urea decomposition device with a cyclone particle collector according to claim 1, characterized in that: It also includes a brake kinetic energy recovery device electrically connected to the controller, the brake kinetic energy recovery device including a transmission device connected to the wheel and a kinetic energy to electrical energy conversion device connected to the transmission device; the controller uses the electrical energy generated by the brake kinetic energy recovery device to control the heating unit.

4. The urea decomposition device with a cyclone particle collector according to claim 1, characterized in that: The inner wall of the cyclone cylinder is coated with a catalyst coating structure, which includes a catalyst coating for urea hydrolysis.

5. The urea decomposition device with a cyclone particle collector according to claim 1, characterized in that: The particle collection bucket contains a collecting substance for sulfate and sulfite ions, which reacts with compounds containing sulfate and sulfite ions to form salts.

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