CN202228159U - SCR urea injection device of diesel engine - Google Patents

Abstract

An SCR urea injection device of a diesel engine belongs to the technical field of engine emission purification treatment. The device comprises a mixing cavity, wherein an air source inlet, a urea inlet and a liquid outlet pipe are arranged on the mixing cavity, the air source inlet is sequentially connected with an air pressure stabilizing valve and an air solenoid valve through a pipeline, a nozzle is fixedly arranged on the urea inlet, a safety pressure limiting valve, a gear pump, a urea filter and a urea tank are sequentially connected on the nozzle through a pipeline, the tail end of the liquid outlet pipe is connected with a mechanical atomizer, and the atomizer is arranged on an exhaust pipe of an external diesel engine. Foretell diesel engine SCR urea injection apparatus, simple structure, reasonable in design. Realize urea aqueous solution's quantitative injection through electromagnetic nozzle, adopt the mode of air assistance simultaneously, with the mechanical type atomizer direct mount of resistant urea corrosion high temperature resistance on the blast pipe of high temperature, promote the reliability of system.

Description

A Diesel Engine SCR Urea Injection Device

technical field

The utility model belongs to the technical field of engine exhaust purification treatment, and in particular relates to a urea quantitative injection device for a selective catalytic reduction system (Selective Catalyst Reduction) used to reduce _NOx emissions of diesel engines.

Background technique

Since its inception, diesel engines have been widely used in various power plants, ships and vehicles due to their good power, economy and durability. Various methods have been used to purify the two main pollutants of diesel engines, particulate matter (PM) and nitrogen oxides (NO _x ). Among them, SCR technology is a very effective method to reduce _NOx emission from diesel engine. Diesel engine SCR post-treatment technology is to use urea aqueous solution as a reducing agent to inject into the exhaust of diesel engines. Under the action of exhaust gas temperature and air flow, urea releases ammonia (NH ₃ ) through pyrolysis and hydrolysis, and reacts with catalyst at a certain temperature Under this condition, NO _x is reduced to nitrogen (N ₂ ) and water (H ₂ O), so as to achieve the purpose of reducing NO _x emissions.

In the current SCR injection urea solution system, the urea electromagnetic nozzle is often installed directly on the exhaust pipe. Since the electromagnetic nozzle is an electronic component, the high exhaust temperature of the engine will cause damage to the urea electromagnetic nozzle, and the urea electromagnetic nozzle must be cooled. The disclosed technology uses urea solution to cool the urea electromagnetic nozzle. After the urea solution exchanges heat with the electromagnetic nozzle and the exhaust pipe, the temperature will inevitably rise, resulting in a change in the density of urea and affecting the precision and accuracy of injection metering. The effect requires cooling of the urea solution or changing the injection metering according to the change of urea density. the

In addition, the urea electromagnetic nozzle is often directly installed in the exhaust pipe, and the exhaust pressure of the diesel engine fluctuates greatly. The urea injection system lacks effective measures to stabilize the pressure wave in the pipeline in front of the urea electromagnetic nozzle, resulting in large fluctuations in the injection volume of urea. Accuracy and Less stable. the

Utility model content

Aiming at the problems existing in the prior art, the purpose of the utility model is to design and provide a technical solution of a diesel engine SCR urea injection device. The injection device has the advantages of simple structure, good injection effect, high accuracy and stability. the

The described SCR urea injection device for diesel engine is characterized in that it comprises a mixing chamber, on which an air source inlet, a urea inlet and a liquid outlet pipe are arranged, and the air source inlet is sequentially connected with an air regulator valve and an air A solenoid valve, the urea inlet is fixed with a nozzle, the nozzle is connected with a safety pressure limiting valve, a gear pump, a urea filter and a urea tank in sequence, and the tail end of the outlet pipe is connected with a mechanical atomizer, The atomizer is arranged on the exhaust pipe of the external diesel engine. the

The above-mentioned SCR urea injection device for a diesel engine is characterized in that one end of the safety pressure limiting valve is connected to a urea tank in a pipeline loop. the

The said SCR urea injection device for diesel engine is characterized in that said safety pressure limiting valve is a mechanical pressure limiting valve. the

The above-mentioned SCR urea injection device for diesel engine is characterized in that a pressure sensor is arranged on the pipeline between the safety pressure limiting valve and the nozzle. the

The said SCR urea injection device for diesel engine is characterized in that said gear pump is a magnetic gear pump driven by a 24V DC power supply brushless motor or a stepping motor. the

Compared with the prior art: 1) The gear pump of the utility model adopts a magnetic coupling of rare earth permanent magnet material to transmit power, that is, a magnetic gear pump that transmits torque without mechanical contact is selected. Its flow is directly related to the speed of the pump, small in size, light in weight, simple in structure, and easy to manufacture and maintain. The magnetic gear pump has no leakage at all, good reliability, and can be reversed, which is very beneficial to the "back pumping" of the SCR urea injection system. The magnetic gear pump can be driven by a brushless motor or a stepping motor with a 24V DC power supply, and the control is simple and precise. the

2) The safety pressure limiting valve adopts a mechanical pressure limiting valve, which has a simple structure and is easy to control. The safety pressure limiting valve recirculates excess urea aqueous solution to ensure that the pressure of the outflowing urea aqueous solution is always stable at the pressure required for spraying by the set nozzle. the

3) The electromagnetic nozzle is not directly installed on the exhaust pipe of the diesel engine, but installed in the mixing chamber, so that the electromagnetic nozzle will not directly contact the high-temperature exhaust gas, and there is no need to cool the electromagnetic nozzle, so the reliability is relatively improved. the

4) The mechanical atomizer is a high-efficiency atomization device suitable for air-assisted methods. The atomizer is made of heat-resistant stainless steel that is resistant to urea corrosion. There is no electronic component that does not need to be cooled, and it has high temperature resistance and high reliability. the

5) Adopt the "double nozzle" method, that is, the electromagnetic nozzle + mechanical atomizer to realize the precise injection and efficient atomization of the urea aqueous solution. the

The above-mentioned SCR urea injection device for a diesel engine has a simple structure and a reasonable design. Quantitative injection of urea aqueous solution is realized through electromagnetic nozzles. At the same time, the air-assisted method is used to install the urea corrosion-resistant and high-temperature mechanical atomizer directly on the high-temperature exhaust pipe to improve the reliability of the system. the

Description of drawings

Fig. 1 is the structural representation of the utility model. the

In the figure: 1-urea tank, 2-urea filter, 3-gear pump, 4-safety pressure limiting valve, 5-pressure sensor, 6-nozzle, 7-mixing chamber, 8-exhaust pipe, 9-air Solenoid valve, 10-air regulator valve, 11-liquid outlet pipe, 12-atomizer. the

Detailed ways

The utility model will be further described below in conjunction with the accompanying drawings. the

As shown in the figure, a diesel engine SCR urea injection device includes a mixing chamber 7 on which a gas source inlet, a urea inlet and a liquid outlet pipe 11 are arranged. the

The air source inlet of the mixing chamber 7 is sequentially connected with an air pressure stabilizing valve 10 and an air solenoid valve 9 . the

A nozzle 6 is fixedly arranged on the urea inlet of the mixing chamber 7 , and the nozzle 6 is placed in the inner cavity of the mixing chamber 7 . The pipeline on the nozzle 6 is connected to the safety pressure limiting valve 4, which is a mechanical pressure limiting valve, and one end of the safety pressure limiting valve 4 is connected to the urea tank 1 at the same time; the pipeline of the safety pressure limiting valve 4 is connected to the gear pump 3. The gear pump 3 is a magnetic gear pump driven by a 24V DC power supply brushless motor or a stepping motor; And a pressure sensor 5 is arranged on the pipeline between the safety pressure limiting valve 4 and the nozzle 6 . the

The mixing chamber 7 is sequentially connected to the liquid outlet pipe 11 and the atomizer 12, and the atomizer 12 is installed on the exhaust pipe 8 of the external diesel engine, and sprays the gas source and the urea mixture in the mixing chamber 7 into the exhaust pipe 8. the

In order to reduce the cost and shorten the pipeline connection between the components, the utility model combines the urea filter 2, the gear pump 3, the safety pressure limiting valve 4, the pressure sensor 5, the nozzle 6, the mixing chamber 7, the air solenoid valve 9, the air The pressure regulator valve 10 is integrated into a small box. the

When working, the gear pump 3 pumps the urea aqueous solution in the urea tank 1 into the safety pressure limiting valve 4 through the urea filter 2, and establishes a pressure exceeding the urea aqueous solution in the pipeline between the gear pump 3 and the safety pressure limiting valve 4. Jet pressure. The urea aqueous solution is divided at the safety pressure limiting valve 4, a part flows back into the urea tank 1 through the liquid return pipe, and the other part flows to the urea nozzle 6. The safety pressure limiting valve 4 plays the role of pressure limiting and pressure stabilization at the same time, ensuring that the pressure of the urea aqueous solution flowing to the urea nozzle 6 is stable at the required injection pressure, and the pressure sensor 5 detects the pressure at the same time. The nozzle 6 arranged in the mixing chamber 7 performs constant-pressure quantitative injection under the control strategy of the controller. The air source provided by the diesel vehicle passes through the air solenoid valve 9 and the air regulator valve 10 to form a stabilized air source, and then fully mixes with the quantitative urea aqueous solution sprayed into the nozzle 6 in the mixing chamber 7, and the mixture of the two is mechanically Type atomizer 12 sprays into the exhaust pipe 8. the

Claims (5)

1. diesel SCR urea-spray device; It is characterized in that comprising mixing chamber (7); Gas source inlet, urea import and drain pipe (11) are set on the mixing chamber (7); On the described gas source inlet successively pipeline connect air pressure maintaining valve (10) and air solenoid valve (9), fixedly install nozzle (6) in the described urea import, pipeline attachment security pressure-limit valve (4), gear pump (3), urea filter cleaner (2) and urea tank (1) successively on the nozzle (6); Described drain pipe (11) tail end connects mechanical type atomizer (12), and atomizer (12) is arranged on the outlet pipe (8) of outside diesel engine.

2. a kind of diesel SCR urea-spray device as claimed in claim 1 is characterized in that described safety pressure-limiting valve (4) one end pipeline loops connect urea tank (1).

3. a kind of diesel SCR urea-spray device as claimed in claim 1 is characterized in that described safety pressure-limiting valve (4) is the mechanical type pressure-limit valve.

4. a kind of diesel SCR urea-spray device as claimed in claim 1 is characterized in that on the pipeline between described safety pressure-limiting valve (4) and the nozzle (6) pressure transducer (5) being set.

5. a kind of diesel SCR urea-spray device as claimed in claim 1 is characterized in that described gear pump (3) is the brushless electric machine of 24V DC electrical source or stepper motor driven magnetic-gear pump.

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