Injection rate control system of ammonia gas generation metering injection device

Abstract

The invention discloses an injection rate control system of an ammonia gas generation metering injection device. The injection rate control system of the ammonia gas generation metering injection device comprises a flow instruction calculation module, a target value calculation module, a model module, a second-stage PWM duty ratio calculation module and a third-stage PWM duty ratio generation module, wherein the flow instruction calculation module calculates and obtains a gas flow instruction according to an ammonia injection rate instruction RNH3 generated by SCR control and the ammonia content CNH3_457 in an ammonia generation chamber; the target value calculation module calculates to obtain a pulse width target value; the model module calculates to obtain the current pulse width signal;the second-stage PWM duty ratio calculation module calculates to obtain a second-stage PWM duty ratio value Dc2 according to an error value obtained by comparing the pulse width target value with thecurrent pulse width signal and a second-stage PWM period value P2; and the third-stage PWM duty ratio generation module generates a third-stage PWM duty ratio value Dc3 according to the second-stagePWM duty ratio value Dc2. The injection rate control system of the ammonia gas generation metering injection device can accurately control the injection rate of ammonia gas.

Description

technical field [0001] The invention relates to an ammonia gas injection rate control system, in particular to an ammonia gas generation metering injection rate control system. Background technique [0002] Selective catalytic reduction (SCR) technology has been widely used to reduce NOx emissions from internal combustion engines, especially diesel engines. In an SCR system, it is generally necessary to mix ammonia (NH3) with the exhaust of the engine and then pass it through a catalyst where the ammonia reacts with NOx in the exhaust and reduces the NOx to nitrogen and water. Due to safety concerns and difficulties in transportation and storage, in SCR systems, ammonia is usually generated from precursors (such as urea) rather than being used directly. Precursors are also referred to herein as reducing agents. [0003] Both solid and liquid reductants can be used in SCR systems. Solid reducing agents can be directly decomposed to produce ammonia, such as metal amine salt...

AI Technical Summary

Problems solved by technology

Therefore, when these ammonium salts are used as reducing agents, if only the mass flow rate of the effluent is controlled, the metering injection will also be inaccurate due to changes in the ammonia content.

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