阅读说明：本技术 一种可变进气截面scr混合器系统 (SCR mixer system with variable air inlet section ) 是由 陈晖� 陆顺 李玟锋 刘家峰 于 2021-06-03 设计创作，主要内容包括：本发明分开了一种可变进气截面SCR混合器系统,本发明可使发动机不同工况下SCR混合器进出口的压差保持在一定的范围,SCR混合器内气体流动能保持在较高的流速,同时,在SCR气体流道内设计了旋转破碎板,提高尿素分解效率,并使尿素分解后氨气与尾气混合更充分的,提高了尾气与氨气的混合均匀性,并能有效降低柴油机在低温工况的尿素结晶风险。(The invention discloses an SCR mixer system with a variable air inlet section, which can keep the pressure difference of an inlet and an outlet of an SCR mixer in a certain range under different working conditions of an engine, keep the gas flow in the SCR mixer at a higher flow speed, and simultaneously design a rotary crushing plate in an SCR gas flow passage, thereby improving the urea decomposition efficiency, leading ammonia gas and tail gas after urea decomposition to be mixed more fully, improving the mixing uniformity of the tail gas and the ammonia gas and effectively reducing the urea crystallization risk of the diesel engine under the low-temperature working condition.)

1. An SCR mixer system with a variable air inlet section is characterized by comprising a mixer shell, wherein an air inlet baffle, an air flue flow guide circular tube and an air outlet baffle are sequentially arranged in the mixer shell from an air inlet direction to an air outlet direction; a urea injection seat is arranged on the mixer shell, and a urea injector is arranged on the urea injection seat; the mixer is characterized in that a rotary liquid drop crushing plate and an air passage partition plate are further mounted inside the mixer shell, the air passage partition plate is respectively connected with an air inlet baffle plate, an air outlet baffle plate and an air passage diversion circular pipe, an opening is further formed in the air passage diversion circular pipe, and the air passage partition plate is mounted beside the opening; the two ends of the rotary liquid drop crushing plate are respectively connected with the air inlet baffle plate and the air outlet baffle plate in a rotating mode, and the installation position of the rotary liquid drop crushing plate is matched with the installation position of the urea injector, so that urea injected by the urea injector passes through the rotary liquid drop crushing plate; the both ends of air flue water conservancy diversion pipe are the opening design to its both ends respectively with the baffle that admits air, go out the baffle and be connected, the baffle that admits air seals the opening of its one end, the baffle of giving vent to anger is equipped with the gas outlet, and the opening of cooperation air flue water conservancy diversion pipe other end can make gas flow from air flue water conservancy diversion pipe inside.

2. The SCR mixer system of claim 1, wherein the mixer housing is provided with a motor, an output shaft of the motor is connected with the intake air deflector, and an opening and closing angle of the intake air deflector is changed by operation of the motor.

3. The variable intake cross-section SCR mixer system of claim 2, wherein said mixer housing further comprises an inlet pressure sensor and an outlet pressure sensor for measuring the pressure at the inlet and the outlet, respectively, said inlet pressure sensor and said outlet pressure sensor being electrically connected to the controller, respectively, for transmitting the collected signals to the controller, said motor being electrically connected to the controller, and the operation of said motor being controlled by the controller.

4. A variable intake cross-section SCR mixer system according to any one of claims 1-3, wherein the rotating droplet breakplates are coated with a heat conducting material.

5. A variable inlet cross-section SCR mixer system according to any one of claims 1 to 3, wherein said rotating droplet breakplates are rotatably connected at both ends to the inlet baffle and the outlet baffle by means of bearings, preferably high temperature bearings.

6. A variable inlet cross-section SCR mixer system according to any one of claims 1 to 3, wherein the mixer housing is further provided with a rectifying plate which is mounted on the outside of the outlet baffle.

Technical Field

The invention relates to the technical field of engine exhaust systems, in particular to an SCR mixer system with a variable air intake section.

Background

The diesel engine post-treatment system in the sixth stage of China mainly comprises a catalytic oxidation unit (DOC), a particle trap (DPF), a selective catalytic reduction unit (SCR) and an ammonia elimination catalyst (ASC), wherein the SCR mixer is taken as an important component of the SCR and is generally arranged at the front end of an SCR carrier, and the SCR mixer is used for promoting urea decomposition and improving the mixing uniformity of tail gas and ammonia gas. However, because the exhaust temperature and pressure change of the tail gas of the engine are large under different working conditions, the lower the gas temperature is, the smaller the gas flow rate is, the larger the crystallization risk of the mixer is, and the existing SCR structure is difficult to meet the condition that urea is decomposed under different working conditions, and the low-temperature crystallization condition is easy to occur.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide the SCR mixer with the variable air inlet section, so that the pressure difference of the inlet and the outlet of the SCR mixer is kept in a certain range under different working conditions of an engine, the gas flow in the SCR mixer can be kept at a high flow speed, meanwhile, a rotary crushing plate is designed in an SCR gas flow passage, the urea decomposition efficiency is improved, the ammonia gas and the tail gas are mixed more fully after the urea is decomposed, the mixing uniformity of the tail gas and the ammonia gas is improved, and the urea crystallization risk of a diesel engine under a low-temperature working condition can be effectively reduced.

The invention adopts the specific technical scheme that:

an SCR mixer system with a variable air inlet section comprises a mixer shell, wherein an air inlet baffle, an air flue flow guide circular tube and an air outlet baffle are sequentially arranged in the mixer shell from an air inlet direction to an air outlet direction, an air inlet guide plate is connected to the air inlet baffle, the air inlet guide plate is connected with the air inlet baffle in a rotating opening-closing manner, a gap between the air inlet guide plate and the air inlet baffle is an air inlet, and the size of the air inlet is controlled by adjusting the opening-closing angle of the air inlet guide plate; a urea injection seat is arranged on the mixer shell, and a urea injector is arranged on the urea injection seat; the mixer is characterized in that a rotary liquid drop crushing plate and an air passage partition plate are further mounted inside the mixer shell, the air passage partition plate is respectively connected with an air inlet baffle plate, an air outlet baffle plate and an air passage diversion circular pipe, an opening is further formed in the air passage diversion circular pipe, and the air passage partition plate is mounted beside the opening; the two ends of the rotary liquid drop crushing plate are respectively connected with the air inlet baffle plate and the air outlet baffle plate in a rotating mode, and the installation position of the rotary liquid drop crushing plate is matched with the installation position of the urea injector, so that urea injected by the urea injector passes through the rotary liquid drop crushing plate; the both ends of air flue water conservancy diversion pipe are the opening design to its both ends respectively with the baffle that admits air, go out the baffle and be connected, the baffle that admits air seals the opening of its one end, the baffle of giving vent to anger is equipped with the gas outlet, and the opening of cooperation air flue water conservancy diversion pipe other end can make gas flow from air flue water conservancy diversion pipe inside.

Furthermore, a motor is arranged on the mixer shell, an output shaft of the motor is connected with the air inlet guide plate, and the opening and closing angle of the air inlet guide plate is changed through the operation of the motor.

Further, still install inlet pressure sensor and outlet pressure sensor on the blender casing, be used for surveying the pressure value of import and export respectively, inlet pressure sensor and outlet pressure sensor are connected with the controller electricity respectively, and the signal that will gather passes to the controller, the motor is connected with the controller electricity, and its operation is controlled by the controller.

Further, the rotating droplet breakplates are coated with a thermally conductive material.

Furthermore, two ends of the rotary liquid drop crushing plate are respectively and rotatably connected with the air inlet baffle plate and the air outlet baffle plate through bearings, and the bearings are preferably high-temperature-resistant bearings.

Further, the mixer shell is also provided with a rectifying plate, and the rectifying plate is installed on the outer side of the air outlet baffle.

The invention has the beneficial effects that: the rotatable air inlet guide plate is designed, the rotation angle of the air inlet guide plate is adjusted according to the pressure difference of the SCR mixer, the tail gas of the engine under different working conditions flows through the SCR mixer at a higher speed, and the crystallization risk under the low-flow-rate working condition is reduced; the rotary liquid drop crushing piece effectively promotes the crushing of liquid drops through the impact of the rotary liquid drop crushing piece and urea liquid drops, and meanwhile, the urea liquid drops deposited on the crushing blade are easier to peel off under the action of centrifugal force, so that the crystallization risk is reduced, and high-speed rotary air flow is formed due to the turbulent flow effect generated by the rotation of the liquid drop crushing piece, and the urea liquid drops are wrapped to flow along with the rotation of the urea liquid drops, so that the urea liquid drops are more fully evaporated and pyrolyzed in limited mixing time, and the mixing uniformity of tail gas and ammonia gas is improved; the invention designs the rectifying plate at the outlet, thereby improving the uniformity of ammonia gas distribution.

Drawings

FIG. 1 is a schematic diagram of the overall structure of a variable intake section SCR mixer system;

FIG. 2 is a schematic illustration of the internal construction of a variable intake cross-section SCR mixer system;

FIG. 3 is a partial cross-sectional view of a variable intake section SCR mixer system;

fig. 4 is a schematic structural diagram of the circular airway guiding tube.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1-2, an embodiment of the present invention provides an SCR mixer system with a variable intake cross section, which includes a mixer housing 1, an intake baffle 2, an air flue diversion circular tube 3, and an outlet baffle 4 are sequentially disposed in the mixer housing 1 from an intake direction to an outlet direction, the intake baffle 2 is connected with an intake air deflector 5, the intake air deflector 5 is connected with the intake air baffle 2 in a rotating opening and closing manner, a gap between the intake air deflector 5 and the intake air baffle 2 is an air inlet, the size of the air inlet is controlled by adjusting an opening and closing angle of the intake air deflector 5, a motor 6 is disposed on the mixer housing 1, an output shaft of the motor 6 is connected with the intake air deflector 5, the opening and closing angle 15 of the intake air deflector 5 is changed by the operation of the motor 6, and the mixer housing 1 is further provided with an intake pressure sensor 7 and an outlet pressure sensor 8, the motor 6 is electrically connected with the controller and is controlled to operate by the controller; a urea injection seat 9 is arranged on the mixer shell 1, and a urea injector 10 is arranged on the urea injection seat 9; the mixer shell 1 is also internally provided with a rotary liquid drop crushing plate 11 and an air passage partition plate 12, the air passage partition plate 12 is respectively connected with the air inlet baffle 2, the air outlet baffle 4 and the air passage diversion circular tube 3, the air passage diversion circular tube 3 is also provided with an opening 13 (shown in figures 3-4), and the air passage partition plate 12 is arranged at the side of the opening 13; the two ends of the rotary droplet crushing plate 11 are respectively connected with the air inlet baffle plate 2 and the air outlet baffle plate 4 in a rotating manner, and particularly are connected with the air inlet baffle plate 2 and the air outlet baffle plate 4 in a rotating manner through bearings 16, and the bearings are preferably high-temperature-resistant bearings. The installation position of the rotary droplet breaking plate 11 is matched with the installation position of the urea injector 10, so that urea injected by the urea injector 10 passes through the rotary droplet breaking plate 11, and the rotary droplet breaking plate 11 is coated with heat conduction materials (the heat conduction materials can enable the temperature of the breaking pieces to rise faster, so that the urea injected onto the rotary breaking pieces is easier to pyrolyze, and the urea is further prevented from crystallizing on the breaking pieces); the both ends of air flue water conservancy diversion pipe 3 are the opening design to its both ends respectively with inlet baffle 2, go out the baffle and be connected, inlet baffle 2 seals the opening of its one end, the baffle 4 of giving vent to anger is equipped with the gas outlet, and the opening of the 3 other ends of cooperation air flue water conservancy diversion pipe can make gas flow out from air flue water conservancy diversion pipe 3 is inside. The mixer shell is also provided with a rectifying plate 14, and the rectifying plate 14 is arranged on the outer side of the air outlet baffle 4

The working flow of the variable intake section SCR mixer system provided by the above embodiment is as follows:

1. tail gas flows into the SCR mixer through an inlet at the air inlet baffle under the action of an air inlet guide plate;

2. after tail gas enters the SCR mixer, a urea injector arranged on the urea injection seat injects urea aqueous solution, and the urea aqueous solution is crushed, evaporated and pyrolyzed into ammonia gas under the action of the rotary liquid drop crushing piece and the tail gas.

3. And tail gas and ammonia gas flow through the rotary liquid drop crushing pieces and push the rotary liquid drop crushing pieces to rotate, and the tail gas and the ammonia gas are uniformly mixed due to airflow disturbance generated by the rotation of the crushing pieces.

5. The mixed gas of tail gas and ammonia flows around the air flue flow guide circular tube, and when the mixed gas reaches the position of the air flue partition plate, the mixed gas flows into the opening on the side due to the blocking of the air flue partition plate, enters the air flue flow guide circular tube, flows out through the outlet on the air outlet baffle plate, and flows into the SCR carrier after passing through the rectifying plate.

6. When the air inlet guide plate controller detects that the difference value between the inlet pressure and the outlet pressure is lower than a set minimum value and the inlet pressure is also lower than the set minimum value, the controller controls the motor to increase the opening and closing angle of the air inlet guide plate until the pressure difference is higher than the set minimum value; when the controller detects that the difference value of the inlet pressure and the outlet pressure is greater than the set highest value, the controller controls the motor to reduce the opening and closing angle of the air inlet guide plate until the pressure difference is lower than the set lowest value.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes in the embodiments and/or modifications of the invention can be made, and equivalents and modifications of some features of the invention can be made without departing from the spirit and scope of the invention.