Selective catalytic reduction (SCR) metering injection pump urea crystal dissolving device

Abstract

The invention discloses a selective catalytic reduction (SCR) metering injection pump urea crystal dissolving device which comprises a pump body and a mixing cavity installed inside the pump body, the side wall of the mixing cavity is provided with an orifice, the pump body is further provided with a flow guide pipeline, at least one chamber is formed inside the pump body, the chamber is communicated with the orifice, one end of the flow guide pipeline is communicated with fluid, and the other end of the flow guide pipeline is communicated with the chamber. The SCR metering injection pump urea crystal dissolving device is simple in structure and ingenious in design, and only purified water is required to be injected into the flow guide pipeline to dissolve reducing agent crystal inside the pump body. Meanwhile, dirt inside the SCR metering injection pump urea crystal dissolving device can be washed away, atomized reducing agents are prevented from diffusing into an air cylinder cavity to cause blocking faults of the pump body, and maintenance is convenient.

Description

technical field [0001] The invention relates to a metering jet pump crystal dissolving technology in an SCR system, in particular to a urea crystal dissolving device for an SCR metering jet pump. Background technique [0002] With the promotion and implementation of the "National IV" and "National V" emission standards for motor vehicles in major cities and even the whole country, the SCR technology route has gradually matured, that is, the reducing agent (32.5% urea aqueous solution) is atomized and quantitatively sprayed into the exhaust pipeline , and through the SCR catalyst, the main harmful gas NO in the exhaust gas X It is converted into nitrogen and water and discharged to achieve the purpose of tail gas purification. [0003] The SCR injection system is divided into airless system and air system. Among them, the air injection control system filters and atomizes the reducing agent, and then injects the reducing agent into the exhaust pipe through air assistance. In ...

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Problems solved by technology

[0003] The SCR injection system is divided into airless system and air system. Among them, the air injection control system filters and atomizes the reducing agent, and then injects the reducing agent into the exhaust pipe through air assistance. In the air injection system In the internal mixing structure, a mixing chamber is often set up to pre-mix before the reducing agent is injected, that is, the high-speed air flow passes through the orifice on the side wall of the mixing chamber and the reducing agent injected into the mixing chamber is mixed with gas and liquid, as shown in the Chinese patent The gas control system disclosed in the patent with the announcement number CN201982159U and the name "Air-liquid Mixing Device of Urea Metering Pump in SCR System" has a mixing chamber and an orifice arranged tangentially. On the one hand, the mixing effect is good, and on the other hand, it can Provide injection pressure, however, due to the small diameter of the orifice on the side wall of the mixing chamber, it is easy to be blocked by the returning reducing agent

[0004] In order to prevent the orifice from clogging, the applicant has developed a needle-through anti-blocking structure (the patent application number is: 201120242990.1, and the patent application name is: the anti-blocking device of the air orifice in the SCR injection system). A cylinder chamber is set in the pump body of the pump, and a movable component is set in the cylinder chamber. The movable component drives the needle to move, which can effectively prevent the orifice from being blocked. However, in practice, due to the easy diffusivity of the atomized reducing agent, the The reducing agent will still diffuse into the orifice, and crystallize in the orifice, and even spread to the cylinder chamber where the anti-blocking device is installed. Long-term use will cause a large amount of reducing agent crystallization to accumulate, and the orifice will be blocked, affecting the injection The system works normally; in addition, after the high-speed airflow used for gas-liquid mixing enters the metering jet pump, unfiltered grease in the air will deposit in the pump body, and excessive accumulation will also affect the normal operation of the jet system

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