Turbine front SCR (Selective Catalytic Reduction) after-treatment system

Abstract

The invention discloses a turbine front SCR aftertreatment system which comprises a turbine front SCR which comprises a first air inlet and a first air outlet, and the turbine front SCR can mix urea and gas exhausted by an engine; the switching valve comprises two channels and a valve, and the switching valve can switch the channels through the valve, so that the gas passes through the pre-vortex SCR or does not pass through the pre-vortex SCR; the chassis SCR system comprises a chassis SCR; the urea spraying device comprises a first urea nozzle and a second urea nozzle, the first urea nozzle is connected with the first air inlet of the vortex front SCR, and the second urea nozzle is connected with the chassis SCR. The device is simple and compact in arrangement, does not need to change a whole vehicle mounting interface, can meet better conversion efficiency of NOX under low-temperature and high-temperature working conditions at the same time, effectively reduces the content of NOX in tail gas, and meets the requirements of ultra-low emission regulations.

Description

Technical Field

[0001] The present invention relates to a diesel engine exhaust after-treatment technology, in particular to a pre-turbine SCR after-treatment system. Background Art

[0002] Currently, China's VECC is developing the seventh stage of emission regulations for heavy-duty road vehicles (National VII). Among these, after-treatment systems with SCR (Selective Catalyst Reduction) are the mainstream technology for reducing emissions. Current after-treatment technology routes include electric heating + urea nozzle + close-coupled SCR + DOC + DPF + urea nozzle + SCR + ASC (referred to as two-stage SCR), DOC + nozzle + SDPF + nozzle SCR + ASC (referred to as SCRF dual-injection), and DOC + DPF + electric heating + urea nozzle + SCR + ASC (referred to as single-injection). All three routes require the use of electric heaters. Using these devices requires the vehicle to preferably use a 48V circuit, increase the battery capacity and generator power, and significantly modify the vehicle, resulting in a significant increase in cost. Furthermore, the electric heater consumes electricity, which increases the vehicle's fuel consumption.

[0003] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0004] The purpose of the present invention is to provide a pre-turbine SCR post-treatment system that can meet the requirements of low-temperature and high-temperature NOx conversion efficiency and effectively reduce NO in exhaust gas. X content.

[0005] To achieve the above objectives, the present invention provides a pre-turbine SCR after-treatment system, comprising: a pre-turbine SCR, comprising a first air inlet and a first air outlet, the pre-turbine SCR being capable of mixing urea and engine exhaust gas; a switching valve, the switching valve comprising two channels and a valve, the switching valve being capable of switching channels by the valve to allow the gas to pass through the pre-turbine SCR or not pass through the pre-turbine SCR; a chassis SCR system, comprising a chassis SCR; a urea injection device, comprising a first urea nozzle and a second urea nozzle, the first urea nozzle being connected to the first air inlet of the pre-turbine SCR, and the second urea nozzle being connected to the chassis SCR.

[0006] In one embodiment of the present invention, the switching valve further includes a second air inlet, a second air outlet, a third air inlet and a third air outlet, wherein the third air outlet is connected to the first air inlet, the third air inlet is connected to the first air outlet, and the second air outlet is connected to the chassis SCR system; when the valve is open, the gas enters the switching valve through the second air inlet and flows out of the switching valve through the second air outlet; when the valve is closed, the gas enters the switching valve through the second air inlet, flows out of the switching valve through the third air outlet, flows into the pre-turbine SCR through the first air inlet, flows out of the pre-turbine SCR through the first air outlet, and then enters the switching valve through the third air inlet and flows out of the switching valve through the second air outlet.

[0007] In one embodiment of the present invention, the pre-turbine SCR includes a mixing chamber and a reaction chamber, wherein the mixing chamber is capable of mixing urea and gas, and the reaction chamber is capable of causing the mixed gas to undergo a catalytic reduction reaction; one end of the mixing chamber is adjacent to one end of the reaction chamber and is separated by a partition wall, wherein the partition wall is provided with a first through hole; a urea inlet is provided in the mixing chamber, wherein the urea inlet is connected to the first urea nozzle; an intake pipe and a metal carrier are provided in the reaction chamber, wherein one end of the intake pipe is located in the reaction chamber, and the other end passes through the first through hole and extends into the mixing chamber; the length of the intake pipe in the reaction chamber is less than the depth of the reaction chamber; the metal carrier is located between the outer wall of the intake channel and the inner wall of the reaction chamber, an air outlet chamber is provided between one end of the metal carrier and one end of the reaction chamber, an air inlet chamber is provided between the other end of the metal carrier and the other end of the reaction chamber, and the first air outlet is located on the side wall of the air outlet chamber.

[0008] In one embodiment of the present invention, the chassis SCR system comprises: a hydrocarbon injector, a first temperature sensor, a diesel oxidation catalyst, a second temperature sensor, a catalyzed diesel particulate filter, a first NOx sensor, a third temperature sensor, a chassis SCR, a fourth temperature sensor, and a second NOx sensor connected in sequence;

[0009] In one embodiment of the present invention, the diesel oxidation catalyst is integrated with an ammonia slip catalyst.

[0010] In one embodiment of the present invention, a supercharger is further included, and the supercharger is arranged between the pre-turbine SCR and the chassis SCR system.

[0011] In one embodiment of the present invention, an electric heater is further provided between the supercharger and the chassis SCR system. A third NOx sensor and a fifth temperature sensor are provided between the electric heater and the supercharger. A sixth temperature sensor is provided between the electric heater and the chassis SCR system.

[0012] In one embodiment of the present invention, the valve includes a first valve and a second valve.

[0013] In one embodiment of the present invention, the mixing chamber is in the shape of a cylinder, the reaction chamber is in the shape of a cylinder, and the diameter and length of the reaction chamber are greater than the diameter and length of the mixing chamber.

[0014] Compared with the prior art, the present invention provides a pre-turbine SCR after-treatment system, which is provided with a temperature sensor, a pre-turbine SCR, and a switching valve that allows the exhaust gas to pass through or not pass through the pre-turbine SCR according to different temperatures and operating conditions. When the engine needs to respond quickly, the gas does not pass through the switching valve and directly reaches the supercharger, and the gas temperature will not be reduced due to the heat capacity of the pre-turbine SCR. Under high-temperature conditions, the pre-turbine SCR and the chassis SCR can process the gas together, or all of it can be processed by the chassis SCR. During cold start or low-temperature conditions, the valve is closed, and the gas passes through the pre-turbine SCR for ammonia storage and NOX pre-treatment, making full use of the higher exhaust temperature before the supercharger to perform catalytic reduction in the pre-turbine SCR system. The layout is simple and compact, and the vehicle installation interface does not need to be modified. It can simultaneously meet the good NOX conversion efficiency under low-temperature and high-temperature conditions, effectively reduce the NOX content in the exhaust gas, and meet the requirements of ultra-low emission regulations. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 2 is a schematic diagram of a pre-turbine SCR after-treatment system according to one embodiment of the present invention;

[0016] Figure 2 Detailed structural diagram of a valve of a pre-turbine SCR after-treatment system according to one embodiment of the present invention;

[0017] Figure 3 1 is a detailed structural diagram of a pre-turbine SCR of a pre-turbine SCR after-treatment system according to one embodiment of the present invention;

[0018] Figure 4 It is a schematic diagram of a single-spray solution in the prior art;

[0019] Figure 5 It is a schematic diagram of a double-spray solution in the prior art.

[0020] Figure 6 It is a schematic diagram of a two-stage SCR solution in the prior art.

[0021] Description of main reference numerals:

[0022] 1- Pre-turbine SCR, 11- First air inlet, 12- First air outlet, 13- Mixing chamber, 131- Urea inlet, 14- Reaction chamber, 141- Intake pipe, 142- Metal carrier, 143- Outlet chamber, 144- Intake chamber, 15- Partition wall, 16- First through hole, 2- Switching valve, 21- Valve, 22- Second air inlet, 23- Second air outlet, 24- Third air inlet, 25- Third air outlet, 3- Chassis SCR system, 31- Chassis SCR, 32- Hydrocarbon injector, 33- First temperature sensor, 34- Diesel oxidation catalyst, 35- Second temperature sensor, 36- Catalyzed diesel particulate filter, 37- First NOx sensor, 38- Third temperature sensor, 39- Fourth temperature sensor, 391- Second NOx sensor X Sensor, 4-urea injection device, 41-first urea nozzle, 42-second urea nozzle, 5-supercharger, 51-electric heater, 52-third NO X Sensor, 53 - fifth temperature sensor, 54 - sixth temperature sensor. DETAILED DESCRIPTION

[0023] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0024] Unless expressly stated otherwise, throughout the specification and claims, the term "comprise" or variations such as "include" or "comprising", etc., will be understood to include the stated elements or components but not to exclude other elements or other components.

[0025] like Figures 1 to 3 As shown, a pre-turbine SCR after-treatment system according to a preferred embodiment of the present invention includes: a pre-turbine SCR1, including a first air inlet 11 and a first air outlet 12, and the pre-turbine SCR1 can mix urea and the gas exhausted by the engine; a switching valve 2, the switching valve 2 including two channels and a valve 21, the switching valve 2 can switch the channel through the valve 21 to allow the gas to pass through the pre-turbine SCR1 or not pass through the pre-turbine SCR1; a chassis SCR system 3, including a chassis SCR31; a urea injection device 4, including a first urea nozzle 41 and a second urea nozzle 42, the first urea nozzle 41 is connected to the first air inlet 11 of the pre-turbine SCR1, and the second urea nozzle 42 is connected to the chassis SCR31.

[0026] Specifically, the two channels include a first channel in which the gas passes directly from the switching valve 2 and then flows directly to the chassis SCR system 3, and a second channel in which the gas passes from the switching valve 2, enters the pre-turbine SCR1, and then enters the chassis SCR system 3 through the switching valve 2. The opening and closing state of the engine valve 21 can be automatically adjusted according to the temperature and operating conditions. Because the pre-turbine SCR1 has heat capacity, the exhaust gas discharged from the engine will absorb heat and the temperature will be reduced when it flows through the pre-turbine SCR1, which will affect the power response of the engine when the engine needs to quickly increase power output. Therefore, when the engine needs to respond quickly, the valve 21 is opened, and the gas does not pass through the pre-turbine SCR1, but directly reaches the supercharger 5. Under high temperature conditions, the exhaust flow is large. Due to the small size and insufficient processing capacity of the pre-turbine SCR1, the subsequent chassis SCR31 is required to process NOx together, or the pre-turbine SCR1 exits and all NOx emissions are processed by the subsequent SCR. Therefore, the switching valve 2 and the first channel are set up, and the intake channel of the pre-turbine SCR1 system is closed through the valve 21. The gas does not pass through the pre-turbine SCR1 system and flows directly to the supercharger 5. At this time, the chassis SCR system 3 has a better conversion efficiency for higher temperature NOX. During cold start or low temperature conditions, the valve 21 is closed, and the engine exhaust cannot directly enter the supercharger 5. It needs to pass through the pre-turbine SCR1 system for ammonia storage and NO X Pre-treatment, making full use of the higher exhaust temperature before the turbocharger 5 to perform catalytic reduction in the SCR1 before the turbine, reducing NO in the exhaust gas before the turbine X content, reducing NO entering the chassis SCR system 3 X content, thereby simplifying the chassis exhaust after-treatment system.

[0027] As a preferred embodiment, the switching valve 2 also includes a second air inlet 22, a second air outlet 23, a third air inlet 24 and a third air outlet 25, wherein the third air outlet 25 is connected to the first air inlet 11, the third air inlet 24 is connected to the first air outlet 12, and the second air outlet 23 is connected to the chassis SCR system 3; when the valve 21 is opened, the gas enters the switching valve 2 through the second air inlet 22 and flows out of the switching valve 2 through the second air outlet 23; when the valve 21 is closed, the gas enters the switching valve 2 through the second air inlet 22, flows out of the switching valve 2 through the third air outlet 25, flows into the pre-turbine SCR1 through the first air inlet 11, flows out of the pre-turbine SCR1 through the first air outlet 12, and then enters the switching valve 2 through the third air inlet 24 and flows out of the switching valve 2 through the second air outlet 23.

[0028] Specifically, the second air inlet pipe is connected to the preceding pipeline. The first channel of the switching valve 2 is the channel connecting the second air inlet 22 and the second air outlet 23 when the valve 21 is open. The second channel is the pipeline connecting the second air inlet 22 and the third air outlet 25, and the third air inlet 24 and the second air outlet 23 when the valve 21 is closed. In this case, the second air inlet 22, the third air outlet 25, the first air inlet 11, the first air outlet 12, the third air inlet 24, and the second air outlet 23 are sequentially connected to form a pipeline.

[0029] As a preferred embodiment, the pre-turbine SCR1 includes a mixing chamber 13 and a reaction chamber 14, wherein the mixing chamber 13 can mix urea and gas, and the reaction chamber 14 can cause the mixed gas to undergo a catalytic reduction reaction; one end of the mixing chamber 13 is adjacent to one end of the reaction chamber 14 and is separated by a partition wall 15, wherein the partition wall 15 is provided with a first through hole 16, and the mixing chamber 13 is provided with a urea inlet 131, wherein the urea inlet 131 is connected to the first urea nozzle 41; an intake pipe 141 and a metal carrier 142 are provided in the reaction chamber 14, wherein the intake pipe 141 is provided with a metal carrier 142 ... One end of the pipe 141 is located in the reaction chamber 14, and the other end passes through the first through hole 16 and extends into the mixing chamber 13. The length of the air intake pipe 141 in the reaction chamber 14 is less than the depth of the reaction chamber 14; the metal carrier 142 is located between the outer wall of the air intake channel and the inner wall of the reaction chamber 14, and an air outlet cavity 143 is provided between one end of the metal carrier 142 and one end of the reaction chamber 14, and an air intake cavity 144 is provided between the other end of the metal carrier 142 and the other end of the reaction chamber 14, and the first air outlet 12 is located on the side wall of the air outlet cavity 143.

[0030] Specifically, the urea inlet 131 is used to connect the mixing chamber 13 and the first urea nozzle 41, and to introduce the urea in the first urea nozzle 41 into the mixing chamber 13. As a preferred embodiment, the first air inlet 11 is located on the side wall of the mixing chamber 13, the partition wall 15 is located on one side of the mixing chamber 13, and the first urea nozzle 41 is located on the other side of the mixing chamber 13 and on the axis of the cylindrical mixing chamber 13, so as to evenly spray urea into the mixing chamber 13. One end of the metal carrier 142 is flush with one end of the air intake pipe, or shorter than one end of the air intake pipe. There is a certain distance between the metal carrier 142 and both ends of the reaction chamber 14, so that two cavities, an air intake chamber 144 and an air outlet chamber 143, are formed between the two ends. When the mixture of urea and gas passes through the air intake pipe 141 and the air outlet chamber 143 of the reaction chamber 14, it can be fully mixed, and then undergoes a catalytic reduction reaction through the metal carrier 142 to reduce NO in the exhaust gas. XThe reacted gas is located in the gas outlet cavity 143 and can flow out of the pre-turbine SCR1 through the first gas outlet 12 opened on the side wall of the gas outlet cavity 143 .

[0031] As a preferred embodiment, the chassis SCR system 3 includes: a hydrocarbon injector 32, a first temperature sensor 33, a diesel oxidation catalyst 34, a second temperature sensor 35, a catalytic diesel particulate filter 36, a first NO X Sensor 37, third temperature sensor 38, chassis SCR31, fourth temperature sensor 39, second NO X Sensor 391.

[0032] Specifically, the hydrocarbon injector 32 (HC), the first temperature sensor 33, the diesel oxidation catalyst 34 (DOC), the second temperature sensor 35, the catalytic diesel particulate filter 36 (CDPF), the first NO X Sensor 37, third temperature sensor 38, chassis SCR31, fourth temperature sensor 39, second NO X The sensors 391 are connected in sequence.

[0033] As a preferred embodiment, the diesel oxidation catalyst 34 is integrated with an ammonia slip catalyst (ASC).

[0034] As a preferred embodiment, a supercharger 5 is further included, and the supercharger 5 is arranged between the pre-turbine SCR 1 and the chassis SCR system 3.

[0035] Specifically, the SCR is arranged before the supercharger 5 .

[0036] As a preferred embodiment, an electric heater 51 is further included between the supercharger 5 and the chassis SCR system 3, and a third NO X sensor 52 and a fifth temperature sensor 53 , and a sixth temperature sensor 54 is provided between the electric heater 51 and the chassis SCR system 3 .

[0037] Specifically, the fifth temperature sensor 53 can detect the temperature of the gas in the pipeline. If the temperature is low, the valve 21 is opened, and the engine needs to store ammonia and NO through the pre-turbine SCR1 system. X Pretreatment: If the temperature is high, the pre-turbine SCR1 needs to be bypassed due to its heat capacity. The exhaust gas discharged from the engine needs to bypass the pre-turbine SCR1 and directly reach the supercharger 5.

[0038] As a preferred embodiment, the valve 21 includes a No. 1 valve and a No. 2 valve. Specifically, the No. 1 valve and the No. 2 valve together constitute the valve 21.

[0039] As a preferred embodiment, the mixing chamber 13 is in the shape of a cylinder, the reaction chamber 14 is in the shape of a cylinder, and the diameter and length of the reaction chamber 14 are greater than the diameter and length of the mixing chamber 13 .

[0040] Specifically, the bottom surface of the reaction chamber 14 is connected to the top surface of the mixing chamber 13 .

[0041] By adopting the above technical solution, a pre-turbine SCR1 after-treatment system is provided, which is provided with a temperature sensor, a pre-turbine SCR1, and a switching valve 2 that can allow the exhaust gas to pass through or not pass through the pre-turbine SCR1 according to the temperature and working conditions. When the engine needs to respond quickly, the gas does not pass through the switching valve 2, but directly reaches the supercharger 5, and the gas temperature will not be reduced due to the heat capacity of the pre-turbine SCR1. Under high-temperature conditions, the pre-turbine SCR1 and the chassis SCR31 can process the gas together, or all of it can be processed by the chassis SCR31. During cold start or low-temperature conditions, the valve 21 is closed, and the gas passes through the pre-turbine SCR1 for ammonia storage and NO X Pre-treatment, making full use of the higher exhaust temperature before the turbocharger 5 to perform catalytic reduction in the SCR1 system before the turbine. The layout is simple and compact, and the vehicle installation interface does not need to be changed. It can meet the requirements of NO under low and high temperature conditions at the same time. X Good conversion efficiency, effectively reducing NO in tail gas X content, meeting the requirements of ultra-low emission regulations.

[0042] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A turbine pre-SCR post-treatment system, characterized in that: include: A pre-turbine SCR, comprising a first air inlet and a first air outlet, wherein the pre-turbine SCR is capable of mixing urea and exhaust gas from the engine; A switching valve, the switching valve comprising two channels and a valve, the switching valve being capable of switching channels by the valve to allow the gas to pass through the pre-turbine SCR or not pass through the pre-turbine SCR; Chassis SCR system, including chassis SCR; The urea injection device includes a first urea nozzle and a second urea nozzle, wherein the first urea nozzle is connected to the first air inlet of the pre-turbine SCR, and the second urea nozzle is connected to the chassis SCR.

2. The pre-turbine SCR after-treatment system according to claim 1, characterized in that: The switching valve also includes a second air inlet, a second air outlet, a third air inlet and a third air outlet, wherein the third air outlet is connected to the first air inlet, the third air inlet is connected to the first air outlet, and the second air outlet is connected to the chassis SCR system; when the valve is open, the gas enters the switching valve through the second air inlet and flows out of the switching valve through the second air outlet; when the valve is closed, the gas enters the switching valve through the second air inlet, flows out of the switching valve through the third air outlet, flows into the pre-turbine SCR through the first air inlet, flows out of the pre-turbine SCR through the first air outlet, and then enters the switching valve through the third air inlet and flows out of the switching valve through the second air outlet.

3. The pre-turbine SCR after-treatment system according to claim 1, characterized in that: The pre-turbine SCR includes a mixing chamber and a reaction chamber, wherein the mixing chamber can mix urea and gas, and the reaction chamber can cause the mixed gas to undergo a catalytic reduction reaction; one end of the mixing chamber is adjacent to one end of the reaction chamber and is separated by a partition wall, wherein the partition wall is provided with a first through hole; The mixing chamber is provided with a urea inlet, which is connected to the first urea nozzle. The reaction chamber is provided with an air intake pipe and a metal carrier. One end of the air intake pipe is located in the reaction chamber, and the other end passes through the first through hole and extends into the mixing chamber. The length of the air intake pipe in the reaction chamber is less than the depth of the reaction chamber. The metal carrier is located between the outer wall of the air intake channel and the inner wall of the reaction chamber. An air outlet cavity is defined between one end of the metal carrier and one end of the reaction chamber, an air intake cavity is defined between the other end of the metal carrier and the other end of the reaction chamber, and the first air outlet is located on the side wall of the air outlet cavity.

4. The pre-turbine SCR after-treatment system according to claim 1, characterized in that: The chassis SCR system includes: The hydrocarbon injector, the first temperature sensor, the diesel oxidation catalyst, the second temperature sensor, the catalytic diesel particulate filter, the first NO X sensor, third temperature sensor, chassis SCR, fourth temperature sensor, second NO X sensor.

5. The pre-turbine SCR after-treatment system according to claim 4, characterized in that: The diesel oxidation catalyst is integrated with an ammonia slip catalyst.

6. The pre-turbine SCR after-treatment system according to claim 1, characterized in that: The system further includes a supercharger, which is arranged between the pre-turbine SCR system and the chassis SCR system.

7. The pre-turbine SCR after-treatment system according to claim 6, characterized in that: An electric heater is also included between the supercharger and the chassis SCR system, and a third NO is provided between the electric heater and the supercharger. X sensor and a fifth temperature sensor, and a sixth temperature sensor is provided between the electric heater and the chassis SCR system.

8. The pre-turbine SCR after-treatment system according to claim 1, characterized in that: The valves include valve No. 1 and valve No.

2.

9. The pre-turbine SCR after-treatment system according to claim 3, characterized in that: The mixing chamber is in the shape of a cylinder, the reaction chamber is in the shape of a cylinder, and the diameter and length of the reaction chamber are greater than the diameter and length of the mixing chamber.

Images