A control method of a mechanical nozzle type ammonia injection system

Abstract

The invention discloses a mechanical spray nozzle type ammonia gas injection system used for tail gas treatment of an automobile diesel engine. The mechanical spray nozzle type ammonia gas injection system comprises a liquid ammonia tank, a liquid level temperature sensor, an electric heating rod, an ammonia gas decompressor, a pressure stabilizing tank, a pressure temperature sensor, an electric-control ammonia gas metering valve, a mechanical ammonia gas spray nozzle and a controller, wherein the liquid ammonia tank is fixedly arranged on a frame; the liquid level temperature sensor and the electric heating rod are integrated in the liquid ammonia tank which is connected with the ammonia gas decompressor through a pipeline; the ammonia gas decompressor is connected with the pressure stabilizing tank through a pipeline; the pressure temperature sensor is integrated on the pressure stabilizing tank; the pressure stabilizing tank is connected with an electric-control ammonia gas metering valve; the electric-control ammonia gas metering valve and the mechanical ammonia gas spray nozzle are separately arranged; the mechanical ammonia gas spray nozzle is directly mounted on a gas exhaust tube; the electric-control ammonia gas metering valve is in pipeline connection with the mechanical ammonia gas spray nozzle; and the controller is electrically connected with the liquid level temperature sensor, the electric heating rod, the pressure temperature sensor and the electric-control ammonia gas metering valve separately. The invention also discloses a control method for the mechanical spray nozzle type ammonia gas injection system.

Description

technical field [0001] The invention belongs to a vehicle diesel engine exhaust post-treatment system. Liquid ammonia is used as a reducing agent for diesel nitrogen oxides (NOx), in particular to a mechanical nozzle type ammonia injection system for vehicle diesel engine exhaust gas treatment. Background technique [0002] With the implementation of the National IV emission regulations for commercial vehicles, the vehicle must be equipped with after-treatment devices for nitrogen oxide (NOx) emissions. [0003] China's medium and heavy-duty diesel engines generally adopt the selective catalytic reduction (SCR) technology route, that is, the standard vehicle urea aqueous solution is injected into the exhaust, and the ammonia gas (NH 3 ) for selective catalytic reduction of NOx to produce harmless nitrogen (N 2 ) and water (H 2 O). [0004] Urea solution has obvious disadvantages as a reducing agent: it freezes in winter and needs more than half an hour of heating to thaw ...

AI Technical Summary

Problems solved by technology

[0004] Urea solution has obvious disadvantages as a reducing agent: it freezes in winter and needs more than half an hour of heating to thaw before it can work normally; low temperature performance is poor, and a high exhaust temperature is required to fully convert into NH 3 , when running under urban conditions with low exhaust gas temperature, it is necessary to add insulation materials to the exhaust pipe and install a burner in front of the catalytic converter to increase the temperature to ensure sufficient conversion of urea, otherwise it is easy to generate a large number of crystals, resulting in exhaust gas The pipeline is blocked, which affects the operation of the vehicle; the urea production process is high in energy consumption and high pollution, and the ratio of vehicle urea aqueous solution requires pure water, and the pure water production process consumes 3 times the normal water

Images