Explosion-proof SCR structure
By using the explosion-proof SCR structure, the problem of excessive NOx emissions from diesel engines while meeting explosion-proof requirements has been solved, achieving effective reduction of NOx and optimization of engine performance, while reducing system maintenance costs and fuel consumption.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-06
- Publication Date
- 2026-04-10
AI Technical Summary
Modern diesel engines cannot meet the latest emission standards' NOx limits by relying solely on in-engine purification technology. High EGR rates lead to decreased combustion efficiency, increased particulate matter, and poor power response. They also result in high system reliability and maintenance costs, frequent EGR valve sticking failures, DOC precious metal coating failure affecting DPF regeneration, low efficiency at low temperatures, difficulty in cold starts, EGR cooler leaks causing engine overheating, the need for precise EGR rate control, and incomplete combustion at low speeds, leading to increased fuel consumption.
It adopts an explosion-proof SCR structure, including a diesel engine body, an explosion-proof turbocharger, an explosion-proof exhaust pipe, an explosion-proof aftertreatment system, an explosion-proof water tank, a urea tank, a urea pump, and a potted urea nozzle. It is equipped with temperature sensors and nitrogen oxide sensors, and reduces NOx through urea injection. The SCR structure meets explosion-proof requirements and optimizes engine performance and fuel economy.
It achieves significant reduction in NOx emissions, optimized engine performance and fuel economy, reduced dependence on diesel fuel, avoids the defects of high EGR rate, improves system reliability and reduces maintenance costs while meeting explosion-proof requirements.
Smart Images
Figure CN121827984A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of diesel engine exhaust gas treatment technology, specifically to an explosion-proof SCR structure. Background Technology
[0002] Currently, the system used to reduce exhaust pollutants in non-road China IV diesel engines is: exhaust gas recirculation + oxidation catalyst + particulate filter. Exhaust gas recirculation introduces some exhaust gas back into the combustion chamber, thereby reducing NOx emissions. The oxidation catalyst reduces CO emissions, and the particulate filter reduces particulate matter emissions.
[0003] Modern diesel engines, relying solely on in-engine purification technology, are no longer sufficient to meet the latest emission standards' NOx limits. While a high EGR rate can lower combustion temperature and thus reduce NOx formation, it also leads to decreased combustion efficiency, increased particulate matter, poorer power response, and reduced fuel economy. Furthermore, the system has high reliability and maintenance costs; EGR valves can become stuck, and fully opening or closing the EGR valve can cause a surge in NOx emissions. Failure of the DOC precious metal coating reduces the conversion of NO to NO2, affecting DPF regeneration. The DPF needs to be periodically cleaned at high temperatures to burn off carbon deposits; if regeneration fails, manual cleaning or replacement of the DPF is necessary, which is costly. Low-sulfur diesel fuel must be used to prevent DOC / DPF sulfur poisoning, and low-ash lubricating oil is required to reduce DPF ash accumulation. EGR is inefficient at low temperatures, and DOC and DPF require temperatures above 250°C to function effectively. It also has low cold-start efficiency, and leaks of antifreeze from the EGR cooler can lead to engine overheating. The EGR rate needs to be precisely controlled, as excessive EGR opening at low speeds can cause incomplete combustion. Real-time adjustment of the EGR opening and turbocharging is necessary. While EGR reduces combustion temperature and suppresses NOx formation, it sacrifices power and increases fuel consumption. Therefore, an anti-knock SCR structure is proposed. Summary of the Invention
[0004] The purpose of this invention is to provide an explosion-proof SCR structure to address the shortcomings mentioned in the background art. Modern diesel engines, relying solely on in-engine purification technology, can no longer meet the latest emission standards' NOx limits. While a high EGR rate can lower combustion temperature and thus reduce NOx formation, it also leads to decreased combustion efficiency, increased particulate matter, poorer power response, and reduced fuel economy. Furthermore, the system has high reliability and maintenance costs; EGR valves can become stuck; and fully opening or closing the EGR valve can cause a surge in NOx emissions. Failure of the DOC precious metal coating reduces the conversion of NO to NO2, affecting DPF regeneration. The DPF needs to be periodically cleaned at high temperatures to burn off carbon deposits; if regeneration fails, manual cleaning or replacement of the DPF is required, which is costly. Low-sulfur diesel fuel is needed to prevent DOC / DPF sulfur poisoning, and low-ash lubricating oil is required to reduce DPF ash accumulation. EGR is inefficient at low temperatures, and DOC and DPF require temperatures above 250°C to function effectively. It also has low cold-start efficiency, and leaks of antifreeze from the EGR cooler can lead to engine overheating. The EGR rate needs to be precisely controlled, as excessive EGR opening at low speeds can cause incomplete combustion. The EGR opening and turbocharger need to be adjusted in real time. While EGR lowers the combustion temperature and suppresses NOx formation, it sacrifices power and increases fuel consumption.
[0005] To achieve the above objectives, the present invention provides the following technical solution: an explosion-proof SCR structure, comprising a diesel engine body, an explosion-proof turbocharger, an explosion-proof exhaust pipe, an explosion-proof aftertreatment unit, an explosion-proof water tank, a urea tank, a urea pump, and a cast-type urea nozzle. The diesel engine body is connected to the explosion-proof turbocharger, the explosion-proof turbocharger is connected to the explosion-proof exhaust pipe, the explosion-proof exhaust pipe is connected to the explosion-proof aftertreatment unit, the explosion-proof aftertreatment unit is connected to the explosion-proof water tank, the urea tank is connected to the urea pump, the urea pump is connected to the cast-type urea nozzle, and the cast-type urea nozzle is mounted on the explosion-proof exhaust pipe. The explosion-proof aftertreatment unit is equipped with a catalyst, the explosion-proof exhaust pipe is equipped with a first temperature sensor on the outside, the explosion-proof aftertreatment unit is equipped with a second temperature sensor and a nitrogen-oxygen sensor on the outside, and the explosion-proof exhaust pipe is fitted with a water jacket.
[0006] Preferably, the first temperature sensor is located at the front end of the catalyst, the second temperature sensor is located at the rear end of the catalyst, and the nitrogen and oxygen sensor is located at the rear end of the second temperature sensor.
[0007] Preferably, an air compressor is installed on the diesel engine body, the air compressor is connected to the explosion-proof water tank, and the explosion-proof water tank is connected to a water replenishment tank through a pipeline.
[0008] Preferably, the diesel engine body is connected to an intercooler, the intercooler is connected to a compressor, and the compressor is connected to an air filter.
[0009] Preferably, the urea tank and the urea pump are connected by a suction pipe and a return pipe, respectively.
[0010] Preferably, a liquid level sensor is installed inside the urea tank, and a third temperature sensor is installed on the urea tank.
[0011] Preferably, the liquid level sensor is connected to an explosion-proof electrical control box, and the electrical signal output terminal of the liquid level sensor is connected to the electrical signal input terminal of the explosion-proof electrical control box.
[0012] Preferably, the electrical signal output terminal of the explosion-proof electrical control box is connected to the electrical signal input terminal of the potting urea nozzle.
[0013] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects: 1. The present invention uses a first temperature sensor and a second temperature sensor installed on the explosion-proof exhaust pipe before and after the catalyst, and has an explosion-proof housing structure, to detect the exhaust temperature and thus control the urea injection amount; the urea tank is equipped with a third temperature sensor and a liquid level sensor, which can detect the temperature and remaining amount of urea solution, and prevent urea from freezing or being insufficient, which would lead to a decrease in purification effect.
[0014] 2. This invention provides an explosion-proof diesel engine that meets both explosion-proof requirements and non-road China IV diesel engine emission standards, and has a complete SCR structure that meets explosion-proof requirements. Compared with the EGR+DOC+DPF route, it can significantly reduce NOx emissions, while optimizing engine performance and fuel economy, and reducing dependence on diesel fuel. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0016] Figure 1 This is a schematic diagram of the diesel engine structure of the present invention; Figure 2 This is a schematic diagram of the SCR system of the present invention.
[0017] Explanation of reference numerals in the attached drawings: 1. Diesel engine block; 2. Explosion-proof turbocharger; 3. Explosion-proof exhaust pipe; 31. Catalyst; 32. First temperature sensor; 33. Second temperature sensor; 34. Nitrogen-oxygen sensor; 35. Water jacket; 4. Explosion-proof aftertreatment unit; 5. Explosion-proof water tank; 6. Urea tank; 7. Urea pump; 8. Cast urea nozzle; 9. Air filter; 10. Compressor; 11. Intercooler; 12. Air compressor; 13. Make-up water tank; 14. Intake pipe; 15. Explosion-proof electrical control box; 16. Liquid level sensor; 17. Third temperature sensor; 18. Return pipe. Detailed Implementation
[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0019] In current technologies, diesel engines relying solely on in-engine purification technology are insufficient to meet the latest emission standards' NOx limits. While a high EGR rate can lower combustion temperature and thus reduce NOx formation, it also leads to decreased combustion efficiency, increased particulate matter, poorer power response, and reduced fuel economy. Furthermore, the system suffers from high reliability and maintenance costs; EGR valves can become stuck, and fully opening or closing the EGR valve can cause a surge in NOx emissions. Failure of the DOC precious metal coating reduces the conversion of NO to NO2, affecting DPF regeneration. The DPF needs to be periodically cleaned at high temperatures to burn off carbon deposits; if regeneration fails, manual cleaning or replacement of the DPF is necessary, which is costly. Therefore, low-sulfur diesel fuel must be used to prevent DOC / DPF sulfur poisoning, and low-ash lubricating oil is required to reduce DPF ash accumulation. EGR is inefficient at low temperatures, and DOC and DPF require temperatures above 250°C to function effectively. It also has low cold-start efficiency, and leaks of antifreeze from the EGR cooler can lead to engine overheating. The EGR rate needs to be precisely controlled, as excessive EGR opening at low speeds can cause incomplete combustion. The EGR opening and turbocharger need to be adjusted in real time. While EGR lowers the combustion temperature and suppresses NOx formation, it sacrifices power and increases fuel consumption.
[0020] Example Please see Figure 1-2This invention provides a technical solution: an explosion-proof SCR structure, comprising a diesel engine body 1, an explosion-proof turbocharger 2, an explosion-proof exhaust pipe 3, an explosion-proof aftertreatment system 4, an explosion-proof water tank 5, a urea tank 6, a urea pump 7, and a potted urea nozzle 8. The diesel engine body 1 is connected to the explosion-proof turbocharger 2, the explosion-proof turbocharger 2 is connected to the explosion-proof exhaust pipe 3, the explosion-proof exhaust pipe 3 is connected to the explosion-proof aftertreatment system 4, the explosion-proof aftertreatment system 4 is connected to the explosion-proof water tank 5, the urea tank 6 is connected to the urea pump 7, and the urea pump 7 is connected to the potted urea nozzle 8. The nozzles 8 are connected, and the encapsulated urea nozzles 8 are installed on the explosion-proof exhaust pipe 3. The urea tank 6 and the urea pump 7 are respectively connected by a suction pipe 14 and a return pipe 18. Under a certain NOx concentration and exhaust temperature, the urea pump 7 draws the urea solution inside the urea tank 6 through the suction pipe 14, and then sprays the urea solution into the explosion-proof exhaust pipe 3 through the pipeline. The urea solution decomposes into NH3 and CO2 at high temperature. NH3 acts as a reducing agent to convert NOx into non-polluting N2 and water. Excess NH3 will also be oxidized into N2. The chemical reactions that occur in SCR are as follows: Urea hydrolysis: (NH2)2CO + H2O → 2NH3 + CO2 NOx reduction: NO + NO₂ + 2NH₃ → 2N₂ + 3H₂O Oxidation of NH3: 4NH3 + 4NO + O2 + → 4N2 + 6H2O NH3 oxidation: 4NH3 + 2NO2 + O2 + → 3N2 + 6H2O The explosion-proof aftertreatment unit 4 has a catalyst 31 installed inside, a first temperature sensor 32 installed on the outside of the explosion-proof exhaust pipe 3, a second temperature sensor 33 and a nitrogen-oxygen sensor 34 installed on the outside of the explosion-proof aftertreatment unit 4, and a water jacket 35 sleeved on the outside of the explosion-proof exhaust pipe 3. The explosion-proof exhaust pipe 3 adopts a double-layer design, with the inner layer being ventilated and the outer layer being wrapped with a water jacket 35, which can control the surface temperature of the explosion-proof exhaust pipe 3 to below 150°C and meet the explosion-proof requirements.
[0021] The first temperature sensor 32 is located at the front end of the catalyst 31, and the second temperature sensor 33 is located at the rear end of the catalyst 31. The first temperature sensor 32 and the second temperature sensor 33 are arranged at the front and rear of the catalyst 31, respectively. The first temperature sensor 32 and the second temperature sensor 33 have explosion-proof housings to isolate the inner cavity from the outside world. They are used to detect the exhaust temperature upstream and downstream of the catalyst 31, respectively, to determine the correction of the urea solution injection amount. In order to prevent too much undecomposed urea solution from being injected into the explosion-proof exhaust pipe 3 to crystallize, or to cause too much side reaction to generate ammonium nitrate (NH4NO3) and ammonium nitrite (NH4NO2), the first temperature sensor 32 in front of the catalyst 31 must detect an exhaust temperature of 200°C or higher before allowing urea solution to be injected into the explosion-proof exhaust pipe 3. The nitrogen oxide sensor 34 is located at the rear end of the second temperature sensor 33 and downstream of the catalyst 31. It is used to measure the NOx content in the exhaust gas and transmit the information to the controller via the CAN line. The controller is installed in the explosion-proof electrical control box 15 to meet the explosion-proof requirements.
[0022] An air compressor 12 is installed on the diesel engine body 1. The air compressor 12 supplies air to the starter motor of the diesel engine body 1. The air compressor 12 is connected to the explosion-proof water tank 5. The explosion-proof water tank 5 can collect water from the drain pipe of the air compressor 12. The explosion-proof water tank 5 is connected to a water replenishment tank 13 through a pipe. The explosion-proof water tank 5 is used to cool the exhaust gas at the rear end of the explosion-proof aftertreatment unit 4. The water replenishment tank 13 is used to replenish water to the explosion-proof water tank 5. An intercooler 11 is connected to the diesel engine body 1. The intercooler 11 is connected to the compressor 10. The compressor 10 is connected to the air filter 9. The air filter 9 is used to filter dust and impurities in the air to protect downstream equipment. The compressor 10 is used to compress air and increase gas density. The intercooler 11 is used to cool the high-temperature air after compression and increase the intake air density.
[0023] A liquid level sensor 16 is installed inside the urea tank 6, and a third temperature sensor 17 is installed on the urea tank 6. The liquid level sensor 16 is connected to an explosion-proof electrical control box 15, and its electrical signal output is connected to the electrical signal input of the explosion-proof electrical control box 15. When the liquid level sensor 16 detects a low liquid level in the urea tank 6, it will activate a fault light through the explosion-proof electrical control box 15 to alert the user. When the third temperature sensor 17 inside the urea tank 6 detects a low urea solution temperature, the coolant from the diesel engine 1 will flow through a hot water pipe installed on the outside of the urea tank 6 to maintain the injection temperature of the urea solution. The wiring harness used in the system is intrinsically safe, and the transmitted signals are intrinsically safe, meeting explosion-proof requirements.
[0024] The electrical signal output terminal of the explosion-proof electrical control box 15 is connected to the electrical signal input terminal of the potting urea nozzle 8. The potting urea nozzle 8 is electrically controlled through the explosion-proof electrical control box 15. Moreover, the potting urea nozzle 8 adopts a potting form to meet the explosion-proof requirements.
[0025] In summary, the present invention uses a first temperature sensor 32 and a second temperature sensor 33 installed on the explosion-proof exhaust pipe 3 before and after the catalyst 31, and has an explosion-proof housing structure, to detect the exhaust temperature and thus control the urea injection quantity; the urea tank 6 is equipped with a third temperature sensor 17 and a liquid level sensor 16, which can detect the temperature and remaining amount of urea solution, and prevent urea from freezing or being insufficient, which would lead to a decrease in purification effect.
[0026] This invention provides an explosion-proof diesel engine that meets both explosion-proof requirements and non-road China IV diesel engine emission standards. It also features a complete SCR structure that meets explosion-proof requirements. Compared with the EGR+DOC+DPF route, it can significantly reduce NOx emissions while optimizing engine performance and fuel economy, and reducing dependence on diesel fuel.
[0027] Those skilled in the art will understand that the features described in the various embodiments and / or claims of the present invention can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments and / or claims of the present invention can be combined or combined in various ways without departing from the spirit and teachings of the present invention. All such combinations and / or combinations fall within the scope of the present invention.
Claims
1. An explosion-proof SCR structure, characterized in that, The system includes a diesel engine body (1), an explosion-proof turbocharger (2), an explosion-proof exhaust pipe (3), an explosion-proof aftertreatment unit (4), an explosion-proof water tank (5), a urea tank (6), a urea pump (7), and a potted urea nozzle (8). The diesel engine body (1) is connected to the explosion-proof turbocharger (2), the explosion-proof turbocharger (2) is connected to the explosion-proof exhaust pipe (3), the explosion-proof exhaust pipe (3) is connected to the explosion-proof aftertreatment unit (4), the explosion-proof aftertreatment unit (4) is connected to the explosion-proof water tank (5), the urea tank (6) is connected to the urea pump (7), the urea pump (7) is connected to the potted urea nozzle (8), and the potted urea nozzle (8) is installed on the explosion-proof exhaust pipe (3). The explosion-proof after-processor (4) is equipped with a catalyst (31), the explosion-proof exhaust pipe (3) is equipped with a first temperature sensor (32) on the outside, the explosion-proof after-processor (4) is equipped with a second temperature sensor (33) and a nitrogen-oxygen sensor (34) on the outside, and a water jacket (35) is fitted on the outside of the explosion-proof exhaust pipe (3).
2. The explosion-proof SCR structure according to claim 1, characterized in that, The first temperature sensor (32) is located at the front end of the catalyst (31), the second temperature sensor (33) is located at the rear end of the catalyst (31), and the nitrogen and oxygen sensor (34) is located at the rear end of the second temperature sensor (33).
3. The explosion-proof SCR structure according to claim 1, characterized in that, An air compressor (12) is installed on the diesel engine body (1). The air compressor (12) is connected to the explosion-proof water tank (5). The explosion-proof water tank (5) is connected to a water replenishment tank (13) through a pipeline.
4. The explosion-proof SCR structure according to claim 1, characterized in that, The diesel engine body (1) is connected to an intercooler (11), the intercooler (11) is connected to a compressor (10), and the compressor (10) is connected to an air filter (9).
5. The explosion-proof SCR structure according to claim 1, characterized in that, The urea tank (6) and the urea pump (7) are respectively connected by a suction pipe (14) and a return pipe (18).
6. The explosion-proof SCR structure according to claim 1, characterized in that, A liquid level sensor (16) is installed inside the urea tank (6), and a third temperature sensor (17) is installed on the urea tank (6).
7. The explosion-proof SCR structure according to claim 6, characterized in that, The liquid level sensor (16) is connected to an explosion-proof electrical control box (15), and the electrical signal output terminal of the liquid level sensor (16) is connected to the electrical signal input terminal of the explosion-proof electrical control box (15).
8. The explosion-proof SCR structure according to claim 7, characterized in that, The electrical signal output terminal of the explosion-proof electrical control box (15) is connected to the electrical signal input terminal of the potting urea nozzle (8).